Exam 3

Question 1

What are some of the functions of sound? What does it provide that vision does not?

Answer 1

Sound allows greater awareness of the environemnt that is not directly in our visual field, can alert us to predators or to prey.

Question 2

What are the 2 possible definitions of sound

Answer 2

Physical and perceptual definition

When a tree falls there is always the physical sound but not the perception

Question 3

How is the sound stimulus described in terms of pressure changes in the air?

Answer 3

It is similar to the ripples of a puddle, the aactual particles move only a slight amount

Question 4

What is a pure tone?

Answer 4

a pure tone is a tone with the wave form sine

Question 5

Why was the decibel scale developed to measure amplitude, is decibel perceptual or physical?

Answer 5

Developed to shrink the large scale of possible sound amplitudes into better units based on log, decibel is physical measuring amp

Question 6

What is a complex tone? harmonics? frequency spectra?

Answer 6

Complex tone are tones with multiple harmonics , they are periodic tones like pure tones but their harmonics make them different, the frequency spectra shows a way of indicating a a tones fundamental frequency

Question 7

How does removing one or more harmonics from a complex toe affect the repition rate of the sound stimulus

Answer 7

it doesn’t effect it , the repetition is the same

Question 8

What is the relationship between sound level and loudness?

Answer 8

level is the physical characteristic while loudness is the perceptual characteristic

Question 9

What does the audibility curve show about physical characteristis and perceptual characteristics?

Answer 9

perception requires both the frequency and level to be in a certain range . some frequencies need less decibels to be heard while some need a higher level to be heard

Question 10

What is Pitch in physical characteristics and what are the tone chroma

Answer 10

pitch can be understood as a change in fundamental frequency, Tone chroma is the same fundamental frequencies seperated by multiples of 2 , they create octaves

Question 11

What are the structures of the outer ear

Answer 11

Pinnae, auditory canal and tympanic membrane,

The auditory canal reinforces frequencies at a resonant frequency , this amplifies frequencies between 1,000Hz and 5,000Hz

Question 12

What are the stuctures and functions of the mid ear

Answer 12

Ossicles and oval window, the ossicles the malleus hits the incus and transmits to the stapes which at its footplate attaches to the oval window of the cochlea

Question 13

What are the structures and functions of the inner ear

Answer 13

THe Innear is made up of the cochlea, the cochlea is filled with fluid and is separated by the organ of corti into the upper scala vestibuli and the lower scala tympani,

Question 14

What causes the bending of cilia in hair cellls

Answer 14

Vibrations from the oval window move the organ of corti up and downand causes he tectorial membrane (stretches outer hair cells) side to side.

Question 15

What happens when cilia bend

Answer 15

Inner hair cells, when bent in a certain direction, will fire because of tip links opening ion channels that cause a neurotransmitter release to the auditory nerve fiber

Question 16

How does phase locking cause the electrical signal to follow the timing of the sound stimulus

Answer 16

because the vibration peak correlates with the moving of the cilia into a certain direction.

Question 17

What did Bekesy discover about basiliar membrane vibration

Answer 17

It moves in a traveling wave and it is selective as it filters out certain vibration. high early, low later

Question 18

What is the relationship between sound frequency and basilar membrane vibration

Answer 18

The place of maximum vibration changes its location on the basilar membrane with a change in Hz. low Hz close to apex , high hz close to base

Question 19

What does it mean to say that the cochlea acts as a filter and how does it correlate with a tonotopic map and neural frequency tuning curves

Answer 19

The hair cells respond to certain frequencies better than others. the tonotpic and neural frequency tuning curve shows that some frequencies require a lower threshold to fire a neuron.

Question 20

What is a neurons characteristic frequency

Answer 20

the frequency in which a neuron is most sensitive to

Question 21

How do outer hair cells act as cochlear amplifiers and what was different about cochlear amplification in relation to Bekesy’s discoveries

Answer 21

Bekesy did not perform measurent on living cochlea so it turns out that outer hair cells don’t let ions flow across but elongate and contract in a way that moves the basilar membrane with it, this amplifies certain frequencies better than others.

Question 22

Describe place theory

Answer 22

theory of pitch perception based on the relation between a sound’s frequency and the place along the basilar membrane this activated

Question 23

How was place theory challenged by the effect of the missing fundamental? can it be modified to explain the effect

Answer 23

when the fundamental was removed the pitch did not change, the place where the peak would have been before is now different.
Modification: in a complex tone there will sill be vibration to the remaining harmonics, pitch can be taken from the pattern of places where vibration occurs

Question 24

Burns Viemeister experiment and its implications

Answer 24

challenged even modified version of place theory by amplitude modulated noise.( noise is stimulus with many random frequencies and no vibration pattern , when level was fluctuated pitch was perceived)

Question 25

What is the evidence supporting the idea that pitch perception depends on the timing of auditory nerve firing?

Answer 25

temporal coding by patterns of nerve firing with phase locking as well as its occurence only up to 5000 Hz, which coincides with musical pitch perception.
“THe timing o firing of groups of neurons provides information about the fundamental frequency of a complex ton, and exists if fundamenal frequency of other harmonics are absent.

Question 26

What are resolved and unresolved harmonics and what are their connections with place theory?

Answer 26

Resolved harmonics are low harmonics that can be distinguished very well by the cochlea . Unresolved are harder to distinguish higher harmonics.

because there is correspondence between the place where harmonics filter aligns it with place theory.

Question 27

What problems do Oxen ham’s experiment pose for understanding the physiology of pitch perception?

Answer 27

pitc is perceived beyond 5000 Hz so we don’t know what the fuck is going on. We don’t know the limits of phase locking

Question 28

What is the pathway that leads from the ear to the brain

Answer 28

Auditory pathway by nerve fibers to subcortical structures( cochlear nucleus to superior olivary nucleus in brain stem, inferior colliculus in the midbrain. and Medial geniculate nucleus in the thalamus from MGN to A1) SONIC MG pathway

Question 29

Brain auditory areas

Answer 29

A1 area in temporal love surrounded by core area , then belt area , then just above parabelt area

Question 30

Experiments that suggest a relationship between the firing of neurons in the Auditory cortex and the pitch of complex tones in the marmoset and humans.

Answer 30

Marmosets showed pitch neurons that fire to fundamental frequency. Anterior auditory cortex showed best respondence to pitch perception

Question 31

What is the connection between hair cell damage and hearing loss?

Answer 31

Inner hair cell damage causes a loss of sensitivity, and lose certain frequency discrimination.

Question 32

What is hidden hearing loss

Answer 32

audiogram may not show for nere damage.

Question 33

What is a cochlear implant ? Why do we say that it is a practical application that can be traced to discoveries of basic research.

Answer 33

a cochlear implant works by stimulating place