Please
read chapter 9.
After reading chapter 9, please respond to the following questions:
What were three things from the chapter that you found interesting? Why were they interesting to you? Which one thing did you find the least interesting? Why? What did you read in the chapter that you think will be most useful to in understanding Sensation & Perception? Finally indicate two topics or concepts that you might like more information about.
Note:
Keep in mind that there are no scheduled exams. When you make you posts
make sure they are of sufficient caliber that the could be used as
notes in a test - since the posts are what we are doing in lieu of an
exam. Be sure to use the terms and
terminology in your posts.
While reading chapter 9, I found many concepts regarding the physiology and psychoacoustics of hearing to be very interesting to learn about. I especially enjoyed learning about the basic qualities of sound waves. Sound waves that humans hear are fluctuations in air pressure across time. The magnitude of the pressure change (increase or decrease) in a sound wave is called the amplitude. Amplitude and frequency of sound waves are highly correlated with auditory characteristics. Amplitude is associated with the perceptual quality of loudness. Loudness is the psychological aspect of sound related to perceived intensity or magnitude; while frequency is associated with pitch. Low-frequency sounds correspond to low pitches, and high-frequency sounds correspond to high pitches. Intensity is the amount of sound energy falling on a unit area. These pressure fluctuations can be close together, or spread apart over long periods. Light waves are measured by the distance between the peaks in the waves, but sound waves are described by their patterns of how quickly the pressure fluctuates. Frequency is the number of times per second that a pattern of pressure change repeats, and it is measured in hertz (Hz), where 1 Hz equals one cycle per second. A helpful example given by the textbook was the air pressure in a 500-Hz wave goes from its highest point down to its lowest point and back up to its highest point 500 times every second. I think this is an important concept to learn about, because these concepts are the building blocks to understanding the physiology of hearing. It’s crucial to understand the basics of a concept before one can truly understand more complicated aspects of that concept.
Another concept I enjoyed learning about in chapter 9 was sine waves, complex tones, and fourier analyses. Sine waves, or pure tones, are one of the simplest kinds of sounds. The air pressure in a sine wave changes sinusoidally (continuously) at the same frequency. A sine wave is a waveform for which variation as a function of time is a sine function. The time it takes for one complete cycle of a sine wave is the period of the sine wave, and there are 360 degrees of phase across one period. A phase is the relative position of two or more sine waves. In regard to sound, phase refers to relative position in time. Sine waves are uncommon because few vibrations in our environment are so pure. When taking hearing tests, or using tuning forks, a person can hear sine waves. According to the textbook, flutes can produce musical notes that are close to pure tones but almost every other sound source in the world produces complex tones. A complex tone is a sound wave consisting of more than one sinusoidal component of different frequencies. Despite, pure tones being so rare, it’s important to learn about them because complex tones are varying combinations of sine waves, at different frequencies with different amplitudes. The individual components of a complex sound wave can be described by a process called Fourier analysis, which can be summarized with a graph called a spectrum that illustrates the intensity of each sine wave frequency found in the complex tone. A Fourier analysis is a mathematical theorem by which any sound can be divided into a set of sine waves, and combining these sine waves will reproduce the original sound. I think the concepts of sine waves, complex tones, and fourier analysis were interesting to learn about, and important, because I didn’t realize there were differences in the commonality of pure and complex tones, and that complex tones are varying combinations of sine waves at different frequencies with different amplitudes. I also never knew the mathematical representation of how individual components of complex sound waves are illustrated on a spectrum showing the intensity of each sine wave frequency in the complex tone.
I also found the concept of the physiology of the middle ear interesting to learn about in chapter 9, because I have always enjoyed learning about the anatomy and physiology of the human body and the ear is one of my favorite things to learn about. I used to always study the poster diagrams of the outer, middle, and inner ear at the doctor’s office when I was younger, and still do if they’re available. The outer ear is made up of the pinna, which is the outer, funnel-like portion of the ear, and the ear canal, which conducts sound vibrations from the pinna to the tympanic membrane and prevents damage to the tympanic membrane, or the eardrum. I thought it was interesting to learn that puncturing your eardrum will not lead to deafness in that ear, but that the tympanic membrane will heal itself, but it’s possible to damage it beyond repair so we should still be careful. This tympanic membrane is the border between the outer and middle ear, which consists of three small bones, the ossicles, which amplify sound waves. The malleus, the first ossicle, receives vibration from the tympanic membrane and is attached to the eardrum on one side and to the second ossicle the incus on the other. The incus is connected to the stapes, which transmits the vibrations of sound waves to the oval window of the cochlea, another membrane which represents the border between the middle and inner ear. These ossicles, the smallest bones in the body, amplify vibrations in two ways. The joints between the bones are hinged in a way that makes them work like levers, and this lever action increases the amount of pressure change by about 33%. The second way these tiny bones increase the energy transmitted to the inner ear is by concentrating energy from a larger to a smaller surface area. The tympanic membrane is approximately 18 times larger than the oval window, thus the pressure on the oval window is increased 18 times relative to the pressure on the tympanic membrane. The textbook helpfully related this idea to the principle of how snowshoes are effective for keeping your feet from sinking through the snow and stiletto heels are hazardous to wood floors. It said to relate the heel of the foot to the tympanic membrane and the oval window to the tip of the stiletto heel, which was a very effective example in helping me to better understand this concept.
I also think it’s important to learn about this concept because the amplification provided by the ossicles is essential to our ability to hear quiet sounds. The inner ear is made up of a collection of fluid-filled chambers, important because without the fluid the sound waves that were transmitted to the oval window directly would bounce back without moving the oval window at all. The ossicles are also important for loud noises, too. The middle ear has two muscles attached to the tiny bones. The tensor tympani, attached to the malleus, and the stapedius, attached to the stapes, have the responsibility of tensing when sounds are very loud by decreasing vibration, which restricts the movement of the ossicles and muffles the pressure changes that might be so great as to damage the delicate structures in the inner ear. The disadvantage of this acoustic reflex is that it follows the onset of loud sounds by about one-fifth of a second. This means it helps in environments that have sustained periods of loud noises, but does not protect against abrupt loud sounds, like a gun shot. A very interesting thing I learned about the muscles of the middle ear is that they can also be tensed during swallowing, talking and general body movement, helping to keep the auditory system from being overwhelmed by sounds made by our own bodies.
The concept I found to be the least interesting from chapter 9 was the auditory nerve. Sounds with different frequencies displace different regions of the cochlear partition, and that inner hair cells, extend along a line traveling the length of the cochlear partition. The responses of individual auditory nerve fibers to different frequencies should be related to their place along the cochlear partition. The different fibers selectively respond to different sound frequencies, and selectivity is clearest when sounds are very faint. A threshold tuning curve is a map plotting the thresholds of a neuron or fiber in response to sine waves with varying frequencies at the lowest intensity that will elicit a response. Researchers insert an electrode very close to a single auditory nerve fiber, and then measure the needed intensity of sine waves of different frequencies for the neuron to fire faster than its normal, spontaneous firing rate. The frequency that increases the neuron’s firing rate at the lowest intensity is called the neuron’s characteristic frequency. I understand that this concept is important to understanding sensation and perception related to our auditory system, but I just didn’t find it to be as interesting to learn about as some of the other concepts in the chapter.
I think the physiology of the outer, middle and inner ear will be the most useful to me in helping me understand sensation and perception, because having the knowledge of how the structures of the ear function will help me to understand how my body and brain perceive the sounds in my environment which affects my daily life. I especially think it’s important to understand how the ossicles amplify and decrease vibrations, due to their function of allowing humans to hear quiet and loud sounds, without damaging the delicate structures of the inner ear. The thing I found interesting about the muscles of the middle ear is that they can also be tensed during swallowing, talking and general body movement, helping to keep the auditory system from being overwhelmed by sounds made by our own bodies, this allows our auditory system to focus on sounds in the environment that could be threatening, or need to be acknowledged.
I would like more information about the anatomy and physiology of the outer, middle and inner ear because I found those to be the most interesting things to learn about from the chapter. I would like a video visual representation of how sound waves move through the different areas of the ear to better understand the process and function of our auditory system. I would also like more information about two-tone suppression because I didn’t think the textbook gave much information about the concept. I know that it is a decrease in the firing rate of one auditory nerve fiber due to one tone, when a second tone is presented at the same time. Suppression effects are particularly pronounced when the second tone has a lower frequency than the first tone. The suppression effect appears to be caused by mechanical changes to the basilar membrane. I don’t know if an example of this concept, or maybe just a more detailed explanation would help me to better understand this concept, but I would definitely like more information concerning two-tone suppression.
Terms: psychoacoustics, hearing, sound waves, air pressure, magnitude, pressure change, amplitude, intensity, sound energy, light waves, frequency, hertz, auditory characteristics, loudness, pitch, low-frequency, high-frequency, sine waves, complex, tones, fourier analysis, pure tones, sinusoidally, waveform, sine function, period, phase, complex tones, spectrum, middle ear, pinna, ear canal, tympanic membrane, eardrum, ossicles, malleus, incus, stapes, oval window, cochlea, amplification, inner ear, outer ear, tensor tympani, stapedius, auditory system, auditory nerve, cochlear partition, inner hair cells, threshold tuning curve, neuron, characteristic frequency, two-tone suppression, basilar membrane
Long, through post! Glad you enjoyed the material
What I liked least about this chapter was the constant comparison of light and sound waves and the somewhat interchangeable terminology of the two senses. I found this to be quite confusing and tough to understand exactly which topic they were attempting to discuss. The two terms that caused me the most trouble were amplitude and intensity. These terms are probably very simple to understand but the author wrote about them in a difficult way that was hard for me to understand. The one interesting part of the introduction that did actually help me out a lot was the metaphor on page 220 that said that sound is similar to a rock hitting a pond. This allowed me to visualize how sound works and vibrates into signals that our brain can convert into useful information. I am more excited for the upcoming chapters that are more relevant to daily life such as learning to listen and how the brain deciphers speech.
Despite these issues, there was actually some very fascinating information in this chapter. I enjoyed learning about the complex structure of the ear. The three parts that I found to be most interesting were the tympanic membrane, which is the part of the ear known more widely as the “ear drum.” The tympanic membrane is made up of a skin layer of skin and is deep within the ear canal so that it cannot easily be damaged. What I liked about the tympanic membrane was a question that came to mind. The book says that it vibrates and thus creates sound. Can you actually see the membrane vibrate if you can get close enough or are the vibrations so small that the human eye cannot notice them? I am hoping to figure this out in my topical blog for Thursday. With the eardrum comes the ossicles, which are 3 tiny bones located in the ear. It amazes me that tiny little bones have the special power of amplifying sound. The human body never stops amazing me! The third and final interesting ear structure that I found interesting is also the piece of information from this chapter that I believe will also aid me in my understanding of S&P is the cochlear partition. Throughout reading this chapter, I have become more and more interested in how our brain interprets sound, which is what the cochlear partition does but interpreting neural signals. It just makes me wonder how the brain can take tiny sound particles and understand what they mean, especially when it comes to language. Beyond this, I was interested in this part of the ear because I have heard of cochlear implants, which I believe are a kind of hearing aid.
Hearing loss is a life situation that has recently become important to me. My boyfriend’s grandfather gradually lost his hearing with age, as is his father, and maybe it’s just me but I am fairly confident that my boyfriend is also slowly getting worse and worse at hearing what I say as well. This may actually be a listening issue that comes with the number of years you have been in a relationship (ha ha) but I think it may be more serious than that. Thus, I explored the various hearing impairment that happen to individuals to try and figure out which one could be linked to my boyfriend and his male family members. I decided against otitis media because most often occurs in children who have ear infections, I hope that modern day ear tubes are lessening the number of incidence related to this. I also decided against otosclerosis because it seems more severe and less common than sensorineural hearing loss, which is the most common and makes the most sense. Sensorineural hearing loss happens as hair cells in the ear die. Above I stated one topic that I am interested in learning about and the other is this sensorineural hearing loss because it relates to my life.
Terms: Amplitude, Intensity, Cochlear partition, Cochlear implant, Ossicles, Tympanic Membrane, eardrum, Otosclerosis, Neural signals, Sensorineural hearing loss, and Otitis media.
It is pretty interesting stuff. I am half deaf and can't imagine being 100% deaf! That would be really different.
Chapter 9 was all about the physiology and psycho-acoustics of ears and hearing. The physiological aspects of the ear and hearing I remember studying before in class, but there were a number of other things in this chapter that I found to be far more interesting. Like the smallest bones in the body happen to be in the ears, the ossicales. Three bones in the body that amplify sound vibrations in a number of ways. While those are the smallest bones they are connected to the smallest muscles in the human body located in the middle ear; tensor tympani and stapedius. Tensor tympani are a muscle attached to the malleus, the stapedius attached to the stapes; both muscles tensing decreases vibrations which results in the acoustic reflex. The reflex that protects the ear from intense sounds, via contraction of said muscles. Amazing what just a few bones and muscles can do for ones hearing. Another interesting thing is the location of where our two ears converge. The cochlea, the spiral structure of the inner ear containing the organ Corti, which is in both ears travels to the mid pons, where the superior olive is located. The superior olive is an early brain stem region in the auditory pathway where inputs from both ears converge. Having not really known where the auditory system meets between ears I found this particularly interesting.
The most interesting for me I think was the topic of psycho-acoustics; the study of the psychological correlates of the physical dimensions of acoustics; a branch of psychophysics. People in this sort of research strive and achieve in distinguishing between physical characteristics of sounds and the impression of sounds on listeners. Hertz is a measurement of sound, a physical characteristic these scientists’ measure and which is expressed in frequencies. A frequency is the number of times per second that a pattern of pressure change repeats, while pitch is what listeners here and is the psychological aspect of sound related mainly to the fundamental frequency. In the same case intensity is the physical characteristic; the amount of sound energy falling on a unit of area, it is loudness that a listener hears, which is the psychological aspect of sound related to perceived intensity or magnitude. Fascinating that sound has both a physical characteristic and psychological aspect, I just always took as granted as simple sound.
Probably the least interesting of this chapter was some of the old physiology of the ear as something I went over in biology a while back. So I was familiar with the pinna, the outer, funnel-like part of the ear, and the tymapanic membrane, also called the eardrum being the thin sheet of skin at the end of the outer ear canal, vibrating in response to sounds. The refresher in physical structure of the ear was nice for this class though.
Terms: pinna, tympanic membrane, ossicles, tensor tympani, stapedius, cochlea, hertz, frequency, loudness, pitch, intensity, superior olive, psycho-acoustics, acoustic reflex,
I think the importance of the physio stuff is that it lets you know what an amazing thing the auditory system is! The problem of having to convert an airborne signal to a liquid signal (huge impedance mismatch) and then into a neural signal that we interpret as something loud or soft or high or low or good or bad, is really incredible. Lot going on with auditory perception. Definitely an underrated sense, compared to the amount of work being devoted to vision.
The things I found most interesting in Chapter 9 were the qualities of sound waves, the auditory nerve, and the temporal code for sound frequency. Essentially sound waves are just fluctuations in air pressure across time. The difference between the highest pressure area and lowest pressure area is the amplitude. Sound waves have wavelengths as well. The measurement of the fluctuations of these sound waves is known as frequency. The speed of a fluctuating sound wave is measured in hertz, where one Hz equals one cycle per second. Amplitude and frequency of sound waves are highly correlated. The amplitude is associated with loudness, the more intense a sound wave is, the louder it will sound. Frequency is associated with pitch. Low frequencies are correlated with low pitch, high frequency is associated with high pitch. To describe differences in amplitude across such a wide range of frequencies, we use the units of decibels.
I also found the auditory nerve really interesting. The frequency selectivity is best when the clearest sounds are faint. A threshold tuning curve is a map that plots the thresholds of a neuron or fiver in response to sine waves with varying frequencies at the lowest intensity that will give rise to a response. To graph these curves, researchers insert an electrode very close to a single AN fiber. The frequency that increases the neurons’s firing rate at the lowest intensity is called the neuron’s characteristic frequency. It is important to note that all sounds in the environment are more complex than single sine waves, most sounds we hear are much more quite or louder than what we are able to perceive or measure.
I also found the subject of temporal code for sound frequency interesting as well. Many auditory nerve fibers tend to fire action potentials at one particular area in the phase of a sound wave, a phenomenon called phase locking. Phase locking may occur because AN fibers fire when the stereocilia of hair cells move in one direction but do not fire when the stereocillia move in the other direction. The existence of phase locking means that the firing pattern of an AN nerve fiber carries a temporal code for the sound frequency. A temporal code is the tuning of different parts of the cochlea to different frequencies in which information about the particular frequency of an incoming sound wave is coded by the timing of neural firing as it relates to the period of the sound. The volley principle is an idea stating that multiple neurons can provide a temporal code for frequency if each neuron fires at a distinct point in the period of a sound wave but does not fire on every period.
The thing that I found least interesting was the physiology of the ear. Although learning about the different frequency levels that we can hear and relating them to real life situations like the sound of the library and at what decibel we can hear that at was interesting. The having to relearn the parts of the ear was a bit annoying. The ossicles seems really complex and confusing. I think the take away point from this chapter that will be most helpful in understanding sensation and perception is that humans and other mammals can hear sounds across a wide spectrum of intensities. Not all sound frequencies are heard as being equally loud, but being able to hear across a wide range of intensities is accomplished by the use of many auditory neurons. I would like to learn more about the psychoacoustics section of the chapter.
TERMS: sound waves ,amplitude, frequency, hertz, loudness, pitch, decibels, threshold tuning curve, neuron’s characteristic frequency, sine waves, phase locking, temporal code , cochlea, ossicles, volley principle
Interesting that you picked up on the shearing force of the cilia wherein you get a propogation of the action potential in one direction based on the phase cycle, but not in the other cycles. Good read!
After reading chapter 9 I left somewhat confused. Although this chapter was just supposed to go over the basics of the ear and the auditory system, I think it covered the material a bit too fast. I would have like the authors to go more into the subjects rather than try to bunch it all up in a short chapter. However I did find it helpful that the authors related the material about the auditory system back to the visual system. Majority of the chapter was dry, but I was able to find some interesting concepts and some things I would like to know more about.
I enjoyed reading about low and high spontaneous fibers. This was interesting to me because they fire when there are different types of sound waves. I really enjoyed how the authors related this to the retina and the rods and cones; this made it easier for me to understand. The high spontaneous fibers are like the rods. They respond better to low levels of sound, which also means the reach saturation more quickly (they stop responding when the frequency gets higher). The low spontaneous fibers are like the cones. They respond better to higher levels of sound, but they do not respond to low levels of sound. The level s that are in between the high and low spontaneous fibers cause the mid spontaneous fibers to respond, they capture the sound waves that the high and low spontaneous fibers cannot.
I found the information about psychoacoustics to be interesting. This was interesting to me because researchers of psychoacoustics actually get feedback from the listeners and it’s not just the anatomy of the ear, or what is going on in the auditory system and the brain. The researchers of psychoacoustics look into how humans perceive the physical sound. I found it interesting that intensity and loudness correlate to one another, but they do not match perfectly. For example when we hear something for a long period of time we perceive that sound as being louder than what it actually is, this is known as temporal integration. This concept is also true for frequency and pitch, they correlate with one another, but they are not completely equal.
Another section I found to be interesting was the section about hearing loss. This section was interesting to me because at the beginning of the chapter the authors emphasized how important hearing is, and without hearing it would be very hard to deal with daily life tasks. I also found it interesting that many people have hearing impairments but few are actually deaf. Most hearing impairments can be fixed on their own just by healing like, conductive hearing loss. This is where the middle ear bone cannot convey vibrations from the tympanic membrane to the oval window. Some hearing impairments can also be fixed surgically, like otosclerosis. This is where there is an abnormal growth in the middle ear bone. The most common hearing impairment is the sensorineural hearing impairment, this usually occurs because there is damage to the hair cells.
As I somewhat stated before I found this chapter to be very dry and I became uninterested very fast. I think this is mainly because the information in the chapter was not organized very well. It also seemed that concepts that should be easy to understand were not. If I were to pick something that was the most uninteresting to me I would have to pick the information about the inner ear. I believe that this is very important to know about and understand, but as I was reading it a lot of the information was summed up very quickly. I thought there could have been more time spent on the vocabulary words and how exactly the inner ear functions, rather than clumping all the information one right after another.
While reading the chapter I found the most important concepts that would be beneficial in understanding sensation and perception to be the information about the structure of the ear, most importantly the outer ear, middle ear and inner ear. I believe it is important to know about these structures because they are like the building blocks to finding out more information. If we were not to learn about these structures it would be hard for us to understand the more complex features. Also these are important in understanding how the auditory system works. I believe this is one of the first steps in how humans perceive sound.
I would like to know more information about the valley principle. I would like to know more about this principle because it was not discussed in much depth in the chapter. Also I found this principle to be interesting because the hypothesis is that our neurons can work together to encode higher frequencies that one neuron could not do on its own. I would also like to know more information about the hearing impairments. This was interesting to me because there are so many different kinds. The impairment I would really like to know more about is the conductive hearing loss and how it can be caused by fluid buildup during an infection known as otitis media. I would like to know more about this because as a child I had many ear infections and although the chapter stated this usually heals on its own I would still like to know more about it.
Terms: low and high spontaneous fibers, sound waves, retina, rods, cones, saturation, mid spontaneous fibers, psychoacoustics, intensity, temporal integration, frequency and pitch, , conductive hearing loss, middle ear, otosclerosis, tympanic membrane, oval window, sensorineural hearing impairment, hair cells, inner ear, outer ear, valley principle, otitis media
Think about it this way. It is an amazing feat of nature that the ear can detect and transmit different waves of pressure that can travel (in our case) through the air! Not only that, but the ear converts the airborne medium of sound into a liquid medium and then converts it into a neural signal that you interpret as a song you like, or your mother's voice, or your alarm clock, or your ringtone on your phone. Pretty amazing.
There was a magnitude of subjects that I found interesting in chapter 9, the top 3 however were learning about the inner ear, organ of corti and frequency and pitch. There are multiple structure we must first understand before we can get a good look at the inner ear. The coclea is a tiny coiled structure embedded in the temporal bone of the skull. If the cochlea was uncoiled that it would me 35 mm long. It is filled with a watery fluid in three separate canals. The three canals are the tympanic canal, vestibular and the middle canal. These three canals are separated by two membranes known as the reissner’s and basilar membrane.
The organ of corti is where the movements of the cochlear partition are translated into neural signals by structures. The organ of corti is made up of specialized neurons called hair cells and also dendrites of auditory nerve fibers. Psychoacousticians have studies how listeners perceive pitch. When I’m sitting in my apartment, I can always hear my next door neighbor TV and it drives me crazy! So I try and mask the sound with my own TV. Masking is using a second sound, frequently noise, to make the detection of another sound more difficult. When I turn my TV off then I can immediately hear my neighbors TV.
Something that I didn’t find very interesting was the coding of amplitude. I found is to be a little confusing when the book started talking about the different wave frequencies and place codes. Something I believe will be the most useful in understanding sensation & perception is the two tone suppression. The two tone suppression is the decrease in firing rate of one auditory nerve fiber due to one tone, when a second tone is presented at the same time. Another thing I think that it’s important is rate saturation and rate-intensity function.
Rate saturation is the point at which a nerve fiber is firing as rapidly as possible and further stimulation is incapable of increasing the firing rate. The rate-intensity function is a map plotting the firing rate of an auditory nerve fiber in response to a sound of constant frequency at increasing intensities. Two topics that I would like to learn more about is hearing loss in general, specifically otosclerosis and ototoxic. The second topic is sine waves, complex tones and fourier analysis.
Terms: inner eat, organ of corti, frequency, pitch, cochlea, temporal bone, tympanic canal, vestibular canal, middle canal, reissner’s membrane, basilar membrane, organ of corti, neural signal, hair cells, dendrites, masking, psychacousticians, place codes, rate saturation, rate-intensity function, otosclerosis, ototoxic, sine waves, complex tones, fourier analysis.
Basically, with Fourier analysis, you can decompose or break down the sound wave into smaller components that you might be interested in. You also get these harmonics that emerge based on the fundamental frequency. So, you'll get the propogation of these frequencies after the sound occurs. You can look at the frequencies along a spectrum and use that to figure out what effect the different frequencies have on either your psychoacoustic perception or the actual underlying neural processes giving rise to these perceptions of sound.
One of the first sections of this week's chapter that interested me was the discussion of the fundamental qualities of sound waves - an essential starting point for the rest of the chapter. Though fairly intuitive, it is rather odd to describe sound waves as they truly are - just changes in air pressure over time. I guess that would explain the classic tagline for the movie Alien - "In space, no one can hear you scream." How rapidly these changes in pressure fluctuate describes the frequency of a sound wave, and the difference between the area of highest pressure and that of the lowest pressure is called a wave's intensity or amplitude. The more intense a sound wave, the higher its perceived loudness - which we measure in units known as decibels. Likewise, the frequency of a sound wave (measured in hertz, or cycles per second) results in the perceptual phenomenon we know as pitch.
Surprisingly, one of the more interesting sections for me was the portion of the chapter regarding hearing loss. I think this was mainly because of the large variety of ways in which our auditory system can be damaged. Laypersons so often seem to focus on the potential for damage to the tympanic membrane by loud noises. While this may be quite possible, there are countless other common factors - which makes it fairly silly to focus on the eardrum alone. One of the most common is the loss of hearing due to hair cell damage, a risk that I'm sure many of us have heard about, but is still oddly easy to forget (probably because we do not always focus on these hair cells as part of the basic anatomy). This seems a somewhat staggering omission since the book says we have somewhere around 14,000 of these ultra-sensitive hair cells. Conductive hearing loss, where the bones of the middle ear are damaged or impaired, is a condition that I had not heard much about and find to be quite interesting. I feel that a failure to recognize such a multitude of potential defects does not do justice to the complexity and fragile equilibrium of a healthy auditory system.
Another cool section was the discussion of frequency and pitch. Humans are apparently able to detect differences of as little as one-tenth of a percent between frequencies below 1000 Hz. This ability weakens for pitches above this 1000 Hz threshold, a limitation commonly attributed to a breakdown in the temporal code for frequencies, resulting in a dependence on the pattern of auditory nerve fiber responses from different parts of the cochlea, or place coding. This deficiency may also help to explain why humans tend to perceive greater differences in pitch among lower frequencies than higher ones - the higher frequency system is not nearly as precise. Experimentation has also shown that when masking effects are present from multiple pitch inputs these lower frequencies tend to mask the higher ones, or in other words, the presence of a lower frequency makes it more difficult to perceive higher ones.
This was one of the driest of our recent chapters, but I did still enjoy most of it. However, reading through most of the anatomical descriptions of the auditory system was a bit of a chore. I will not include the section on the inner ear in this criticism, because many of the concepts discussed therein were a bit more specialized and novel. Much of the outer and middle ear sections included major organs that I have heard about for much of my lifetime (excuse the pun). I think my take-home message for this week's chapter is that the ear is just as complex an organ as the eye, but we often take our phenomenal sense of hearing for granted. I would like to learn more about psychoacoustic methodologies.
Terms: sound wave, frequency, amplitude, loudness, decibel, hertz, pitch, hair cell, conductive hearing loss, tympanic membrane, temporal code, auditory nerve fiber, cochlea, place coding, masking effect, psychoacoustics
I think we definitely take it for granted. Most people are very visual and our representations of the world typically have visual descriptions. But, imagine not having an auditory code of representing the world. Would you still have that "inner" voice that you hear yourself either repeating something from your day or replaying some event in your head? You'd have the visual aspect, but a lot of the communicative aspects would lapse, not to mention life without music seems dreadfully dull!
In order for the sound to be processed in the inner ear, it must travel through the ossicles. The ossicles are 3 tiny bones that are located in the middle ear. These bones are intended to amplify sound waves. They are not only the smallest bones and muscles in the human body, but they are vital for protecting the inner ear. The first bone structure in the ossicles is the malleus. The malleus is the first to receive vibration from the tympanic membrane, the eardrum. The malleus then sends this information to the incus. The incus connects the malleus to the stapes. The stapes is the final process in the ossides because it sends the vibrations to the oval window, which leads to the inner ear. I chose to write about this tiny structure because it has two very important purposes: amplification and loud sound protection. The ossicles softens the vibrations so that they can be absorbed by the fluid in the inner ear. If the vibrations are too intense, then the fluid would not absorb them. The ossicles also tense up when loud sounds occur. When they tense up, it is difficult for vibrations to pass through the bones, and thus the inner ear is protected.
The inner ear reminds me of the retina in the eye because it is where the vital sensory processes occur. And, like the retina, it is buried inside of the ear to be kept safe. The cochlea is the major important structure in the inner ear because it not only contains vital processes, but it also protects the sensitive fibers within. One of the most important functions in the cochlea is the organ of Corti. This structure is where auditory information is sent, received and processed. Inside the organ of Corti are hair cells and auditory nerve fibers. Hair cells act as the dendrites for the auditory nerve fiber cells because they send and receive information processed within the auditory nerve fibers. The auditory nerve fibers convey information to the brain stem via the hair cells.
The information processed within the ear are broke down into different waves. Sine waves are the pure, undisrupted sounds. This is the simplest form of sound, but it can also be very difficult to create. Sine waves are initially measured by phases, which is the relative position in time. There are 360 degrees of phases in a period. A period is the time it takes for one cycle to be completed. Sine waves are not a common occurrence in daily activities because pure sounds are hard to come by. Sine tones are applicable because they are used to describe different aspects of complex tones. Complex tones are sounds that we are more likely to experience; they are combinations of several sounds. Each sine wave has its own frequency, amplitude, and phase. Frequency is the number of times the pressure of a sound changes and amplitude is the magnitude of sound pressure. In this context, phase is used to refer to the position of sine waves to one another. So this means that not only are we constantly experiencing several sine waves at a time, complex tones, but that each individual sound has its own properties. The process of separating the complex tones into sine waves is called Fourier analysis.
The Fourier system is not only important in separating sine and complex tones, it is also crucial to determining the timbre of a sound. Timbre is the quality of a sound that can be heard by the human ear, the quality is determined by harmonics. The Fourier analysis is relevant because it separates the sounds onto a spectrum. The spectrum then separates the sounds into various “shapes”. Each sound has its own shape, which the timbre depends on to make accurate judgments on the quality of sound. Or at least this is how I understand this system to work, I found this segment in the book to be extremely confusing. It may be because I have no background in music and no strong interest in the quality of sounds.
In this post, my intention was to write about things that I had never heard of before. Though I did not find this chapter to be very interesting, I still took the time to process the material. I would like more information on the two tone system and more clarity on the functions within the ear. The book seemed to focus heavily on the different structures within the ear, rather than their exact functions.
Terms: inner ear, ossicles, middle ear, sound waves, malleus, tympanic menbrane, incus, stapes, oval window, amplification, retina, cochlea, organ of Corti, hair cells, auditory nerve fibers, sine waves, pure sounds, phase, period, complex tones, frequency, amplitude, fourier analysis, timbre, harmonics,
I like how you related the auditory system to what you've already learned from the visual system. You see the similarities between the two. Both involve physical structures which detect/absorb and transmit/transduce information from the external world into a neural code that we can experience perceptually and phenomenologically and represent internally.
Fourier analysis is incredibly intense, but think of it as breaking down a frequency (say 20 Hz) into various components. Or better yet, think of it as a big wave about to hit the shoreline of a beach. You have the large wave approaching the beach, but you also have ripples that are created as "aftershocks" of that wave once it hits the beach. So you have the initial wave (frequency), and then you have other little waves (called harmonics, etc) that trickle onto the shoreline after the wave hits. So, if you're interested in the effect that wave had on something (say the beach, or how many neurons fired in response to hearing the wave) you can break the wave down into smaller units and find out about what smaller components actually contributed to the overall characteristic or "essence" of that wave. I don't know if that helps at all, but that's an example I've heard before.
Three things I found interesting in this chapter was first the acoustic reflex. An acoustic reflex, according to the text, is a reflex that protects the ear from intense sounds, via contraction of the stapedius and tensor tympani muscles. I just thought this was interesting because I have never heard of it before. I am just amazed with how our body reacts and adapts to protect ourselves from possible harm. This may seem like a minor thing, but I value my hearing so it naturally struck my interest. Another thing I thought was intriguing was rate saturation. Rate saturation is the point at which a nerve fiber is firing rapidly as possible and further stimulation is incapable of increasing the firing rate. It is a little dry to read about, but I just never knew that at a certain point you can max out the nerve fibers firing rate I just thought you just would keep unconsciously increase the firing rate. The third thing I found interesting was otosclerosis, which is an abnormal growth of the middle-ear bones that causes hearing loss. I thought this was neat because I am very interested in how the surgery is performed, because the ear is so complex and delicate. I would like to learn a little more about this condition because the section about it was brief.
The thing from this chapter I found least interesting was the seemingly millions of terms that after a while all started to sound the same. It was a very dry chapter, but I know it is important to know these terms, but it was just a lot at once for me. It is hard for me to say what I think is most useful thing from this chapter in understanding sensation and perception, but I would have to say just knowing the parts of the ear. If you don’t know and understand the terms and parts of the ear this chapter could just as well be written in Spanish. The ear is very complex and knowing the parts and what they do is a major step in understanding sensation and perception.
Topics- otosclerosis and acoustic reflex
Terms- acoustic reflex, stapedius muscle, tensor tympani muscle, rate saturation, nerve fiber, otosclerosis, and middle-ear.
The most important thing is not any individual structure or its function, but the overall integration of all the structures and their function to give you the perception of sound. Sound outside of your ear and brain is just different pressures of air molecules bouncing around based on the intensity of the initial source of moving those air molecules around. BUT, the truly great thing to take away from the chapter is that you somehow get the perception of all the sounds you enjoy or those that help you navigate your environment or survive, etc. etc. because somehow nature formed a sensory system to detect a physical stimulus and transform that stimulus (air) into a mechanism that can pull out the different frequencies present in that stimulus, (liquid filled cochlea) and code the information neurally to give you a rich, effortless perception of the sounds you love, hate, or are indifferent to. That's whats cool about it!
The first couple of pages felt like a review from my physics classes I had taken years ago. But I felt it was easier to understand and remember things like amplitude, intensity, frequency, hertz (Hz), and period when I had to use them in class. To sit down and actually work with the math and see how it all fits together was much more effective then reading it from a book (nothing against the book). I did pretty well in my physic class in high school so I enjoyed getting a refresher on the material, but I enjoyed it more when I had to put it into practice. I actually got to see how it is all put into practice at a concert one time. We got there WAY early and when the sound guys were setting up they were adjusting all of their equipment. They were doing a bunch of test to avoid sound waves cancelling each other out. This happens when one sound wave is coming back from being bounced off a wall (at least in this case) and mixing with or cancelling out another wave. This doesn’t happen all the time but I able to hear it once. For a split second, there just wasn’t any noise (tone). The second part I found interesting (or thing that I have some type of connection with or relate to) was the parts of the inner and middle ear. For anyone who wants a better representation of the tympanic membrane: think of a fully inflated balloon being held next to a speaker. I had to make a model of an ear for one of my science classes back in high school; the tympanic membrane was probably the easiest thing I had to make/put together. I also had to make the Ossicles, semicircular canals, and cochlea. I used some type of Play-Doe stuff and had it all held up by strings. What I didn’t count on was gravity pulling my Malleus, Incus, and Stapes to the bottom of the box. Luckily I was able to fix it before I had to turn it in and I think it lasted long enough for me to get the grade. It’s just another one of those things where for me, reading it just isn’t enough if I really want the material to stick. But those parts of the ear and the physics of sound waves stuck with me because I had to work with it for a close to an entire semester. My third thing was white noise. I honestly thought it’s definition was be something more about a sound wave that we use to fill-in when it is silent and we are just so used to it that we block it out. But my definition sounds much more like masking.
When the inner ear started braking down to the cellular level I started to lose my interest/focus. It just wasn’t as interesting because I could better apply other parts of the ear but at one point it just started to become words on a page. I prefer to work with things hands on.
The different types of hearing loss I think is useful in understanding Sensation and Perception. I thought that hearing loss was just due to the hairs in the inner ear laying down flat, but there are actually many types of hearing loss.
I don’t think I need more information but I would really like to go over the parts in the inner ear again. I was having trouble when the parts started getting smaller. I would also like to know more about the human threshold of hearing.
Terms: amplitude, intensity, frequency, hertz (Hz), period, tone, inner ear, middle ear, tympanic membrane, Ossicles, semicircular canals, cochlea, Malleus, Incus, Stapes, white noise, masking, and threshold of hearing.
The human range of frequencies that we can detect and ultimately perceive is from around 20 Hz (cycles per second, LOW frequencies) to about 20,000 Hz (extremely high that most people can't hear). The high frequencies tend to be inaudible to us after we reach a certain age. Attribute this to the damage we all do to our inner and outer hair cells from music, loud noise, natural wear and tear on the auditory system. There are frequencies up closer to 20,000 Hz that adults can't hear, but teenagers can hear. They call this the "teen buzz" b/c if you play a higher frequency sound (say 17,000 Hz) teenagers often wince or show that look of pain that you get when you hear nails on a chalkboard or some otherwise high-pitch sound derived from a higher frequency. Concerts definitely kill off some of the hair cells if the dB level of the sound from the speakers is over a certain amount.
I didn't enjoy this chapter as much as I had others in the past. I did find the ear structure relatively interesting though. Mammals have a thing called a pinna which is the outer most part of the ear used to funnel sounds into the ear canal. The ear canal conducts the sound to the tympanic membrane or ear drum. The ear drum is just a thin piece of skin that vibrates when it hears sound. It is able to heal itself from minor injuries. After the ear drum there are three smallest bones in the human body known as the ossicles. These small bones act as levers to amplify sounds. These bones are also attached to the the smallest muscles in the human body; tensor tympani and the stapedius. The main job of these muscles is to decrease vibrations that could cause damage to the ear. This is known as the acoustic reflex. After the ossicles bones, you will find the cochlea which is a small snail like structure. In the cochlea are small fluid filled sacks. The cochlea helps decifer the vibrations which tell the brain what the vibrations mean in terms of sound. The auditory nerve also helps in this. I thought the anatomy of the ear was interesting because it really helped me understand how the ear works. However, it I didn't like that it took several times of reading to understand all the different terms and how they are connected to one another.
I also thought it was interesting that over 30 million Americans suffer from some type of hearing loss. That is roughly 10% of all Americans. One possible form of hearing loss is known as conductive hearing loss. This happens when the ossicles bones are obstructed or damaged and are unable to vibrate. This can be caused from mucus during ear infections. The most common form of hearing loss is sensorineural hearing loss. This happens from defects in the cochlea or the auditory nerve. This can because loud noise or by hair loss in the ear. People also tend to lose their hearing as they get older. I thought that this information was interesting because it is a wide spread condition that most certainly effects people that you know.
I also found it interesting that we were given the formula for decibels. I was always aware that higher decibels mean louder sounds, but I wasn't aware that decibels are a ratio of pressure between 2 sounds.
I was unsure about having a negative decibel sound? I am unsure how this can happen and would like to know more about it. I would also like to know some examples?
Terms: pinna, ear canal, tympanic membrane, ossicles, tensor tympani, stapedius, acoustic reflex, cochlea, auditory nerve, conductive hearing loss, sensorineural hearing loss, decibels
The decibel indicates sound intensity, relative to a known reference (usually 0dB). A positive value means it is greater than the reference (magnified), a negative means it less than the reference (attenuated). Also, the decibel is a dimensionless quantity, meaning that it is not bound to a specific physical characteristic, but is most often associated with sound. So you have to disentangle frequencies (sounds) from decibels (typically the intensity). You can have a 10 Hz frequency (low sound) that will be more intense (higher dB) when amplified. Think of some concerts that you go to now days. The bass is a similar frequency whether played through a small amp at home or projected through a huge speaker column. BUT, the intensity (or how much you are adding or subtracting to/from it relative to its reference will give you the dB).
Again you have an electric bass guitar which is almost inaudible when you pluck the lower (thicker) strings because the frequency is so low and there is no initial amplification, but when you plug into an amp, you get a certain intensity from that amplifier that you can adjust the signal of to make it stronger. So lets just say this is Xx dB to begin with before. THEN, you have that amp plugged into another speaker that can give even more intensity relative to your initial dB level. You will have an increase in dB that is independent of the frequency (or perceived pitch). It will just be loud and intense and painful at some point. Check out this chart for examples:
http://www.gcaudio.com/resources/howtos/loudness.html
Something I took interest in was learning the structures of the auditory system. I never really knew that there were so many different components to the ear that help us hear. The pinna is one particularly special part of the auditory systems because it is the very first thing where sound is collected from. The pinna is similar to what a funnel looks like and is located on the outer part of the ear. In regards to the outer ear, there is also the tympanic membrane (more commonly referred to as the ear drum). There was a short paragraph that gave an interesting tidbit of information about a common myth regarding the tympanic membrane. It has been commonly believed that damage to this part of the ear will result in deafness. However, similar to the way other parts of our body, such as skin, heal themselves, so does the tympanic membrane. Though, it still may be possible to severely damage it beyond fixing, so some caution should still be taken. There is a response from this part of the auditory system that vibrates from sound. The next portion of the auditory system is the middle ear. The middle ear is composed of three very tiny bones called the malleus, incus, and stapes. The three bones in the middle ear can also be called the ossicles. These three small bones are important for sending vibrations from the malleus, which is closest to the outer ear, then to the incus, and finally the stapes. Also, probably the most memorable thing from the chapter is that these ossicles are actually the smallest bones in all of the human body. The last structure is the inner ear. The inner ear has a lot of different components that make it up. The definition of the inner ear is a hollow cavity in the temporal bone of the skull and those accompanying structures that lie within the cavity. Those include the cochlea and vestibular canals. One way I was easily able to identify the cochlea was by its snail shape. The cochlea is filled with fluid in the tympanic canal, vestibular canal, and the middle canal. The cochlea is extremely small coiled up, when it resembles the snail shape, but when it is unfolded appears much bigger. A difference of 4mm coiled compared to 35 uncoiled. The thing I found least interesting from the chapter was about psychoacoustics. I was having a little bit of a difficult time trying to gage what is all included in this methodological way to understand hearing. Psychoacoustics is the study of psychological correlates of the physical dimensions of acoustics, according to the text. It sounds interesting since it’s a different type of perspective on how to find results on auditory hearing, though I don’t fully understand everything that comes with this type of study, so I lacked some interest when reading it. All in all I would have to say that learning about the different anatomy parts of the ear is likely to help me most with my understanding of sensation and perception. It’s really important knowledge about the different aspects of the auditory system from the components of outer, middle, and inner ear. They involve such a significant amount of why and how we hear and what all these little pieces do. Furthermore, the auditory brain structures gave me further knowledge on sensation and perception dealing with the auditory system. There are a few things that I would like to do more research and learn about. Those include concepts dealing with hearing loss. Specifically, otitis media, stuck out to me because it’s something that is seen as a common type when children have ear infection. I might also choose to do some expanding on either ototoxic or sensorineural hearing loss. Hearing loss is a serious problem and I want to come to understand more about how hearing can be impaired instead of just old age. Without hearing, the environment we live in would be very difficult to adjust to. While eye sight can treated relatively easy at times, hearing loss is very complex.
Terms: Pinna, tympanic membrane, outer ear, inner ear, middle ear, ossicles, malleus, incus, stapes, psychoacoustics, cochlea, otitis media.
Good points. I think with all the adaptive optics and ways we can treat the visual problems from things like accommodation of the lens or cataracts or whatever, it seems easier to treat some visual abnormalities. With hair cell loss, they don't come back! You have cochlear implants now days that are pretty mainstream, but that seems more invasive that wearing corrective lenses, etc.
Sine waves were an interesting topic in chapter 9. A sine wave is the waveform for which variation as a function of time is a sine function. This is basically a bunch of synchronized waves which form a pure tone. As we know, most tones aren’t synchronized and few tones are sine waves. Instead, most tones are complex tones. Complex tones are sound waves consisting of more than one sinusoidal component of different frequencies. So instead of synchronized waves, these waves fluctuate. The cool thing is that all tones are still made up of individual sine waves. This is explained in fourier analysis, which states that a mathematical theorem by which any sound can be divided into a set of sine waves. Combining these sine waves will reproduce the original sound.
Another topic I found interesting was the structure of the ear. I thought it was really cool how sounds enter the outer ear, are made more intense by the middle ear and then are transformed by the inner ear. It all starts in the pinna, which is the funnel like part of the ear. The sound wave catches in the pinna and then travels down the ear canal to the tympanic membrane or ear drum. The sound wave is then amplified in the ossicles, which are tiny bones in the ear. This is very key for hearing faint sounds. If sounds are too power there are two muscles that can help restrict harmful noise to the inner ear. The tensor tympani and stapedius muscles can muffle large pressure changes that can harm the inner ear. From here on the waves enter the inner ear where it passes through the cochlea and various membranes and canals. Ultimately the waves are then transformed to neural signals in the cochlear partition.
The part about psychoacoustics was another topic of interest to me. Psychoacoustics is the study of the psychological correlates of the physical dimensions of acoustics; a branch of psychophysics. Many of the tests used to determine which neurons are being stimulated in our brains when we hear a specific sounds or tone. Through this we are able to determine are audibility threshold, which is the lowest level of hearing and highest. Through tests were able determine that we can have the same sound waves at different frequencies. This means we hear the same thing just at different levels of loudness. I found all of this interesting because it shows how we are able to discover all this information about the ear.
The section of the chapter that I found least interesting was the auditory nerve. I just didn’t find it as interesting as the rest of the chapter. I had a hard time understanding two tone suppression and Temporal code for sound frequency. There’s a lot of information in this little section and I’m hoping to hear more about it in class.
I think the most useful thing for me in this chapter was learning about the different parts of the ear. It really helped me get a grasp on how a sound wave enters our ear and is transported and transformed into neural signal.
Terms- psychoacoustics, tone suppression, pinna, outer ear, inner ear, middle ear, tympanic membrane, sound wave, sine wave, complex wave, stapedius muscles, ossicles, tensor tympani, cochlea, cochlear partition, fourier analysis.
It is interesting that once we get so far into learning about the ear, we are less interested in the auditory nerve. It seems similar to the optic nerve and there for we are less impressed esp. after we learn about the cochlea and all that is going on with the coding of sounds of different frequencies. The auditory nerve, however, allows the transmission of that neural signal to the brain, where the real magic happens!!!
The first thing I found interesting in chapter 9 was the information about harmonic spectra, fundamental frequency, and timbre. I play the cello and am always hearing people talk bout timbre in orchestra when it comes to the wind section. I am not majoring or minoring in it but I just enjoy playing. Figure 9.6 was very interesting to see the different frequencies of instruments I hear every week! My orchestra professor talks about getting the wind's Timbre right. And from the text, I have now understood that she is talking about the sound quality and the energy levels. You can create so many different kinds of Timbre when playing any instrument as a matter of fact. Some sound good to the ear, and some sound not so good.
The second thing I found interesting was the never ending structure of the ear! I learned a little about the ear in intro to psychology way back when, but I am pretty sure they left out a lot of stuff because this book really get's into EVERY single part! I have never heard, for example of the ossicles. Besides the fact that it is a fun word to say, the ossicles are three tiny bones in the ear; Malleus, Incus, and Stapes. First of all I wasn't even aware that there were bones in our ears. I thought it was all just tissue and muscles, or something. How ignorant I was! And hearing loss is when these bones break, called conductive hearing loss, or when these bones have an abnormal growth called otosclerosis. Any who, there is just so much going on in the ear!
The third thing I found interesting about this chapter was learning about the organ of Corti and hair cells. I have learned in the past, and am not completely sure, but when you spin in circles, the reason you get dizzy is because the hair cells in your ear get un-even, or sway the wrong way, so to get un-dizzy you have to spin the opposite way a few turns. This works for me, and I wonder if it is actually true! I didn't read anything in this chapter that really solved that piece of knowledge I have, but I plan to research it further!
One thing I did not find interesting about this chapter was the bit on amplitude/intensity, frequency, hertz, loudness, pitch, and decibels. I learned about all of that stuff back-in-the-day you could call it. I understand it is a good lead in into the chapter but to be completely honest I skimmed it because I have been learning about that stuff since elementary school. But hey, it's always good to refresh the memory I suppose!
I think the most important thing to know and understand in this chapter when related to sensation and perception would have to be the ear and how it works. All of the parts. What happens when you hear things.
One topic I would like to research further is definitely my little myth on hair cells. I would like to know if the reason we get dizzy when we spin around is because our hair cells are out of wack.
One other topic I would like to further investigate would have to be to learn more about the auditory path way. Like the medial geniculate nucleas, primary auditory cortex (A1), belt area, and parabelt area.
Terms:amplitude/intensity, frequency, hertz, loudness, pitch, decibel,spectrum, harmonic spectrum, fundamental frequency, timbre, ossicle, malleus, incus, stapes, organ of corti, hair cell, auditory nerve fiber, medial geniculate nucleas, primary auditory cortex, belt area, parabelt area, conductive hearing loss, otosclerosis.
I like how you gave examples that are relevant from your own life. That is how it all becomes clear!!! I took this jazz class in college that involved quizzes that made us distinguish timbre of instruments from one another and also jazz styles (fusion, be-bop, etc. etc). I found it was difficult to distinguish two instruments if they had similar frequencies resulting in a similar perception of pitch (like a bassoon versus a contrabasson would be impossible for me). But some of the more common instruments like tenor vs soprano sax were no problem for me due to the different characteristic frequencies associated with them. Its strange how good people get at detecting notes or chords or pitches or keys of music or tones. I have no idea what is what until I'm actually playing a chord, because I have the motor command being acted with my fingers, I usually see it (because I'm not good enough to not look), and I hear it so I know if it sounds right, but if I just heard it without all the other sensory motor integrative cues, I probably wouldn't know. Good examples, good post, sorry for this rant of a response.
Aside from the basic physics of sound, and the physiology of the ear, this chapter does have some interesting topics. Sound is much simpler in a physical sense; however, the perception of sound is on par with the complexity of visual perception. Most research done in sound perception deals with very basic sounds, simple notes with varying frequency and intensity. The most basic sound is a pure tone, or a simple sine wave. In a more natural setting, sound is usually a multitude of tones, each with different complex sine waves. Sound varies by having different frequencies and intensity of fluctuating patterns of pressure. This pressure is taken in by the tympanic membrane, which in turn is amplified by your middle ear bones. From here the pressure is sent into a liquid medium in your inner ear, in which tiny hairs can identify the specificity of the pressure. The tiny hairs then transform this information into neural output. This, in a nutshell, is how hearing works.
What was interesting to me was the Tectorial membrane and how the movement of this membrane corresponds to different responses from the hair cells. The more intense the sound, the further the Tectorial membrane will move, and thus moves the hair cells. The hair cells are very interesting as well because of the way they convert pressure waves into neural energy. As the hair cells bend, a gate opens to let ions depolarize the cell, which like any other neuron releases neurotransmitters. All of the hairs are connected by little strands of proteins, so that if the hair bends further, it will release more gates by pulling at the strands. This is how sounds can be softer or louder. Frequency, on the other hand, is perceived by having different parts of the Tectorial membrane response to different frequencies. By having certain parts respond only to certain frequencies, you A1 can detect what frequencies are being heard.
Another interesting aspect is how perception of sound waves can be somewhat different than the physical world. Perception of loudness and pitch can be swayed by specific notes or specific loudness, and can also be swayed by having more than one note at a time.
The least interesting part of this chapter was the section about hearing loss. This should come to no surprise, as I am consistently more interested in neurology and physiology, and not necessarily abnormal incidences of certain perceptions.
Terms: perception of sound, pure tone, sine wave, frequency, intensity, tectorial membrane, pitch, loudness
I think the most interesting abnormality for me, would be the case of amusia, or the inability to perceive music despite intact sensory capabilities. I would not be lost without some music to have in the background of the daily routines that often occur in life.
My first fascinating topic in chapter 9 is the basic structure of the auditory system. The auditory system seems to be even more complicated than the visual system. I will start with the outer and middle Ear where sound waves are collected by the pinna and funneled through the auditory canal to the tympanic membrane. The tympanic membrane moves back and forth in response to air pressure changes caused by sound waves. This back-and-forth motion is transferred to the middle ear bones , called the malleus, incus, and stapes. The stapes pushes and pulls on the oval window, a small membrane in the wall of the cochlea, which houses the inner ear structures. It is in the inner ear that the actual neural transduction process takes place; at the end of this process, neural signals emerge through the cochlear nerve and are carried to the brain. Next is the inner ear which is a hollow cavity in the temporal bone of the skull, and the structures within this cavity are the cochlea and vestibular canals. The cochlea is really a rolled-up tube divided into three long, thin, fluid-filled chambers called canals. The oval window pushes in and out of one end of the vestibular canal. One of three fluid-filled passages in the cochlea. The vestibular canal extends from the oval window at the base of the cochlea to the helicotrema at the apex. Also called scala vestibuli. This in-and-out motion causes a traveling pressure wave to pass through the fluid in the vestibular canal and around into the tympanic canal. As the wave moves down the vestibular canal, the bulge it produces puts pressure on the middle canal, which in turn triggers another series of events in the cochlear partition that forms the base of the middle canal. The organ of Corti at the base of the cochlear partition is displaced when traveling waves pass through the fluid within the vestibular canal and causes it to bulge out which in return makes the basilar membrane, along with the inner hair cells and outer hair cells, which sit atop the basilar membrane, to move down and then back up. Hairlike bristles called stereocilia extend from the hair cells to the tectorial membrane. Because of the way it is attached to the cochlear partition, the tectorial membrane drags these stereocilia back and forth as the basilar membrane moves up and down. The back-and-forth motion of the stereocilia on the inner hair cells starts a chemical chain reaction that results in a neural impulse being generated by the hair cell. These impulses are transmitted to the brain via auditory nerve fibers, which collect together and emerge from the cochlea in the cochlear nerve.
My second fascinating topic in chapter 9 is hearing loss. My Mom and my youngest sister are deaf in their right ear. What interests is that out of 7 children only one would have loss of hearing and it is in the same ear. The book states that around 30 million Americans suffer some form of hearing impairment. Hearing can be impaired by damage to any of the structures along the chain of auditory processing from the outer ear all the way up the auditory cortex. The simplest way to introduce some hearing loss is to obstruct the ear canal, thus inhibiting the ability of sound waves to exert pressure on the tympanic membrane. This is mentioned in the first paragraph. A type of hearing loss that happens in the middle ear is called conductive hearing loss. Conductive hearing loss occurs when the middle-ear bones lose their ability to freely convey vibrations from the tympanic membrane to the oval window. This hearing loss can be causes often when the middle ear fills with mucus during ear infections. Your ear filling with mucus actually has a name called otitis media. Otitis media is the inflammation of the middle ear. We are lucky that our ear absorbs the mucus back into the surrounding tissues most of the time. Yum! There is a more serious type of conductive hearing loss called otosclerosis. Otosclerosis is cause by abnormal growth of the middle-ear bones, most typically around the oval window next to the stapes. Surgery can free the stapes from these bone growths and improve hearing. But the most common and most serious form of hearing loss is sensorineural hearing loss. This most commonly occurs inside the cochlea and sometimes as a result of damage to the auditory nerve. Hearing loss is a nasty situation especially when it is irreversible or made worse by surgery.
The topics I found least interesting in chapter 9 were the paragraphs on the isointensity curve and the two-tone suppression. An isointensity curve is a map that plots the firing rates of an auditory nerve fiber against varying frequencies at varying intensities. And the two-tone suppression is a decrease in the firing rate of one auditory nerve fiber due to one tone, when a second tone is presented at the same time.
The three things I read about in the chapter that I thought would be the most useful for me in understanding Sensation & Perception was the structure of the auditory system, the auditory nerve and the overview of different hearing loss. The structure and how it is transferred and may be not are pretty main topics on the hearing system. You could have a serious conversation with someone about the ear system after reading chapter 9.
From my own experiences and perspective I think chapter 2 relates a lot to chapter 9. I think this because chapter 2 is about the visual system. When your vision goes other senses like hearing step up to the forefront and become stronger. I know someone who lost his sight to Glaucoma. Glaucoma is the term for a family of medical problems in which the optic nerve is damaged in some way. Since this nerve is the sole carrier of information from the eye to the brain, severe optic nerve damage can result in partial or complete blindness. The most common form of glaucoma affects millions of Americans. It is a progressive disease that can be quite effectively stopped in its earliest stages. However, without a proper eye examination, many people fail to notice that anything is wrong until their vision has reached a point where there is no remedy for it. Hearing, after eyesight is lost, becomes a large part of your everyday ability to lead a semi-normal life.
TERMS: tectorial membrane, auditory system, auditory canal, outer ear, middle ear, tympanic membrane, sound waves, malleus, incus, stapes, oval window, cochlea, neural transduction, cochlear nerve, inner ear, temporal bone, vestibular canals, helicotrema, scala vestibule, tympanic canal, organ of Corti, inner hair cells, basilar membrane, outer hair cells, auditory nerve fibers, hearing loss, auditory cortex, ear canal, Otitis media, Conductive hearing loss, Otosclerosis, sensorineural hearing loss, isointensity curve, two-tone suppression
I can relate. I had an infection of my ear that resulted in having to have invasive surgery (mastoidectomy) to remove the infected tissue so it wouldn't spread to my auditory nerve and brain. As a result I lack hearing sound inputs to my left ear. It is strange how we adapt because I don't remember what it was like to have hearing in both ears. I seem to get along well with one, but some things are more difficult and I have to position myself in my environment to take advantage of where the sound will best hit my good ear. Background noise (bunch of people talking, etc.) can be extremely frustrating and distracting b/c I can't hear relevant conversations or relevant information.
I find the way in which sound is funneled to be processed to be of interest. This whole process is made up of many distinct parts working together and if one were to fail then the entire system would be altered. I also would have never thought that there were so many steps in hearing because it is something that I take for granted and, I am sure that most people who can hear without any problems do also. In the outer ear sounds are collected, in the middle ear vibrations are concentrated and in the inner ear sound pressure is translated into neural signals for the brain. I find the inner inter to be the most interesting however.
The inner ear was the most interesting of the three parts of the ear. It was easy to understand its function because the book quickly compared it to the retina and what it does. In the inner ear is the cochlea which is made up of the tympanic canal, the vestibular canal, and the middle canal. Although the cochlea is the major structure in the inner ear there are definitely many different structures that encompass the inner ear. All of these other things lead to the hair cells which send and receive input to and from the brain.
I found reading about hearing loss to be pretty interesting. Although hearing loss can have a rather larger range I feel that thirty million people suffering from it is a rather large number. I read in the chapter that damage to any of the structures of the ear could lead to hearing loss. I was surprised by that because I always thought that there was one specific spot in the ear that if damage would cause hearing loss. Simple ways that hearing loss can be caused is by obstructing the ear canal. Some people do this on purpose but it can also be done by having too much earwax in ones ear. Another way is stated in the book was conductive hearing loss. This happens because the middle ear is unable to properly pass vibrations on. Otosclerosis is more serious and it is caused when the middle ear bone grows abnormally. One last cause of hearing lost comes from loss or damage to hair cells. This may come from ototoxic drugs or over exposure to noise. As I stated before I never knew that there was such a variation to hearing loss. This section definitely brought up a lot of questions.
What I found to be the least interesting was the section that talked about the coding of amplitude and frequency. I would say that this was the least interesting to me mostly because I did not really comprehend what it was saying. The main point I believe was the place code part. This basically meant that different parts of the cochlea tune to different parts frequencies. What was confusing to me was what was meant by mechanical displacement.
I think that just having a solid general knowledge of how we hear what we hear will be the most beneficial thing to take from the chapter. That being said knowing that the outer middle and inner ear work as a relay system is important. I also think that since why we hear what we hear is important, it is equally important to know why some people struggle to hear. I am glad that there was a section that covered hearing loss and all of the many different factors that can cause it.
The two concepts that I would like to learn more about are hearing loss and psychoacoustics. Through the reading I found both of these things to be really interesting. I feel like it could do me some good to learn about hearing loss because so many people deal with it over the life span. With psychoacoustic I just think I would enjoy learning about some of the test that are done by researchers in this area.
Key terms: conductive hearing loss, otosclerosis, ototoxic, psychoacoustics, inner ear, middle ear, outer ear, retina, tympanic canal, vestibular canal, middle canal, hair cells
I can see how the tuning coding of frequencies would be a bit dry. Just as there are photoreceptors that absorb different wavelengths of light, so to are there different regions along the cochlea that respond to different frequencies of sound. So within the cochlea is the basilar membrane, which is coiled and spiraled into the snail-like shape of the cochlea. But if you were to unfold this you would see that it starts wide (base) and terminates in a smaller, narrower point (apex). The cool thing is that the cochlea is tonotopically organized so to speak, so that the cells along the base of the basilar membrane respond to 20,000 Hz frequencies, and then as you get closer inside of the cochlea along the basilar membrane, the cells respond to lower and lower frequencies up to the point of the apex.
I think it is interesting the way at which sound travels. Sound is actually vibrations of the sound source. Most don’t really think about sound in that sense. What happens is vibrations from the object causes molecules around the object to vibrate and then there are pressure changes. These pressure changes are the waves of sound. . The extent to which these pressure changes displace sound pressure is called amplitude. The intensity is the amount of sound energy falling on a unit area. I really was able to relate to the analogy the book used about throwing a rock into a pond, which causes ripples in the water until eventually it hits something and is able to stop. Sound waves act much like this. The amplitude and intensity in this analogy would be how hard the rock is thrown. Frequency of a sound wave is the number of times per second that the pattern of pressure change repeats. So in the rock and water ripple analogy the frequency could be thought of as the number of ripples produced. It is also interesting that sound waves travel at different passes through different substances. For example, through air sound waves travel 340 meters per second and through water at about 1500 meters per second. This is much faster than light. Thunder and lightning actually happen at the exact same time in the atmosphere but since sound travels faster than light, one is able to hear the thunder before seeing the lightning.
I thought it was interesting that there are different kinds of waves in sound. Sine waves or pure tones are the simplest kind of tone but also the most uncommon. This is a waveform for which variation as a function of time is a sine function. In sine waves the air pressure changes continuously at the same frequency. This goes on for an entire period, the time taken for one complete cycle of a sine wave. During that period there are 360 degrees of phase, which is the relative position of two or more sine waves. Phase refers to the relative position in time. Examples of sine waves are very uncommon. They are found mostly in hearing tests to determine hearing capacity in humans. Flutes can also produce close to pure tones but most sounds are complex tones. Complex tones are sound waves consisting of more than one sinusoidal (continuous) component of different frequencies. Complex tones are a combination of sine waves. Any amount of noise can be broken down into sine waves at different frequencies and amplitudes. Breaking down these complex tones is a process called Fourier analysis. A graph called a spectrum is used to analyze the intensity and the frequency each of the complex tones in a sound. I think it is really cool that we know all of this about sound because it is something we can’t really see, or take apart. It is really cool that we have learned how this works to the point where we can take it apart and figure out each of the little sine waves even in a complex sound.
I also thought the fact that we have an acoustic reflex was really interesting. This is a reflex in the middle ear. The middle ear is an air filled chamber containing the middle bones or ossicles. The middle ear conveys and amplifies vibration from the tympanic membrane (ear drum) to the oval window (opening to the cochlea). There are two muscles in the middle ear, the tensor tympani and the stapedius. The tensor tympani is the muscle attached to the malleus, tensing the sensor tympani decreases vibration. The stapedius is the muscle attached to the stapes in the cochlea, tensing this muscle up decreases vibration. These two muscles are the smallest in our whole body. These two muscles are responsible for out acoustic reflex. If there are loud sounds in our environment these muscles tense up protecting our ear from the loud sounds. However our acoustic reflex does not protect us from abrupt sounds because it takes about one-fifth of a second for the muscles to clench. I also thought it was interesting that often times during swallowing talking and general body movement these muscles sometime clench so we do not get overwhelmed by the sounds that our bodies make. I think it is really interesting that our bodies have a defense for really loud sounds for long periods of time to prevent hearing damage.
One thing I didn’t find as interesting was two-tone suppression. This is the decrease in the firing rate of one auditory nerve fiber due to one tone when a second tone is presented at the same time. So basically if an AN fiber has a CF of 8000 Hz and a 8000 Hz test tone is used a 1000 Hz suppressor tone has a greater effect on the neurons firing rate. I guess I don’t really understand exactly what that means, maybe that is why I didn’t like that part that much.
The part of the chapter I think it most useful in understanding sensation and perception would be the part about the sine and complex waves and also the part about the structure of the ear.
Things I would like to learn more about would be the sonic boom plane stuff discussed in the beginning of the chapter, and also Fourier analysis.
Terms: sound waves, amplitude, intensity, frequency, sine wave, period, phase, complex tones, Fourier analysis, spectrum, acoustic reflex, middle ear, ossicles, tympanic membrane, oval window, cochlea, tensor tympani, stapeduis, malleus, two tone suppression,
Chapter 9-Perceiving color
1. After reading chapter 9 I found that color blindness is very interesting. Before this chapter I knew that men get color blindness easier than women, but I did not know the process of color blindness. Color blindness is when there are problems with the receptors in the retina of the eye. Most of those with this issue see dark blue or dark brown.There are three different kinds of color deficiencies, monochromat, dichromate, and anomalous trichromat. Monochromat needs only one wavelength to match the color and sees only shades of gray. Dichromat uses two wavelengths. Trichromat needs three wavelengths in order to see some colors in the environment. Color blindness can be a sex-linked disorder carried by a woman to her son.
2. The second topic I found interesting is color and wavelength. The wavelength determines different colors. Shorter wavelengths perceives a blue color, medium is green, long is red and long with medium is yellow. And lastly the long, medium and short wave lengths is white. Sometimes when wavelengths is reflected more than others it is selective reflection of different hues of colors. This made me realize that when I am looking at neon or bright colors it may be different wavelengths then when I am looking at a dull color.
3. The third topic I found interesting is color perception under changing light. This was a demonstration activity in the book that I really enjoyed to completely understand color change. I had to view a circle that is illuminated by natural light by a window and then by a lightbulb in a room, and the colors changed. I believe this is because it is sunny out and the light is brighter than the lightbulb in my room, which makes the color lighter than in my room. When I saw the object under a lightbulb it was easier to see all the details of the color then in the bright sunny light.
One thing I found useful is learning about color deficiency because I know many male friends that have this disorder and have trouble dressing. I now can understand those with this disorder what exactly they see and perceive in everyday life.
One thing I did not enjoy reading about in this chapter is understanding the Trichromatic theory. The color matching experiment was different because it had to do with the wavelengths. I want to learn more or do an experiment using this theory to understanding what Thomas Young was trying to propose with normal color vision.
I would like to learn more about adaptive animal coloration because animals adapt to their surroundings by the colors to recognize certain objects. I love learning about animals and it would be interesting to compare and contrast humans with particular species. Another topic I want to learn more about is perceiving color in 3D movies; is it different or the same as viewing other 2D movies?
Chapter 9 in my book is entitled Hearing: Physiology and Psychoacoustics. I already knew by the title of this chapter that I wasn't going to like it very much. I hate physiology behind things because I don't understand it and I don't do well with the human body.
I enjoyed learning some basic qualities of hearing. I honestly don't remember the last time I learned about hearing so it was great to have a review. Amplitude or intensity is described as the magnitude of a sound wave on a specific object. This was good review because I never would have thought about the different levels of a sound wave. I found it helpful to review what frequency is. In sound, frequency is the number of times that a specific intensity of wave repeats itself in one time. Frequency is definitely good to understand when it comes to hearing because it is the whole basis of hearing different sounds or noises. Reviewing pitch reminded me of choir and how pitch has a different meaning when you are singing, but has almost the same definition when it comes to hearing. Pitch is the constant keeping to the same frequency that is wanted.
I didn't fully understand psychoacoustics, but I found this topic more interesting than the rest. Psychoacoustics is the study of how psychological parts correlate to acoustics in the human body. Basically, when we hear, we have both acoustic properties and psychological characteristics that are being pointed out. We partly interpret what we hear with our own perceptions rather than what is really there. I found this fact to be interesting because it almost means that your ears aren't hearing what your brain is thinking. I think that this term relates well to Sensation and Perception because it is all related.
My favorite topic was white noise. I work at a daycare and we talk about how white noise is always good for babies and children because it calms their brains down. This was fun for me to learn from a psychological view instead of from a motherly view. White noise is described as a sensation in which all wavelengths are present and all the frequencies are in equal amounts. I want to look more into this topic and will be using it for my topical blog!
I didn't enjoy the anatomy of hearing. I just hate how many big words and different parts there truly are in the ear. I have a hard enough time remembering the parts of the brain and that is something required for my major!
Amplitude or Intensity, Pitch, Frequency, Psychoacoustics, white noise