Ch. 6.1. Audition

Question 1

Through which mechanism do we perceive low-frequency sounds (up to about 100 Hz)?

Answer 1

At low frequencies, the basilar membrane vibrates in synchrony with the sound waves, and each responding axon in the auditory nerve sends one action potential per sound wave.

Question 2

2. How do we perceive middle-frequency sounds (100 to 4000 Hz)?

Answer 2

At intermediate frequencies, no single axon fires an action potential for each sound wave, but different axons fire for different waves, and so a volley (group) of axons fires for each wave.

Question 3

3. How do we perceive high-frequency sounds (above 4000 Hz)?

Answer 3

At high frequen- cies, the sound causes maximum vibration for the hair cells at one location along the basilar membrane.

Question 4

4. How is the auditory cortex like the visual cortex? 4 ways

Answer 4

(a) Both vision and hearing have “what” and “where” pathways.

(b) Areas in the superior temporal cortex analyze movement of both visual and auditory stimuli. Damage there can cause motion blind- ness or motion deafness.

(c) The visual cortex is essential for visual imagery, and the primary auditory cortex is essential for auditory imagery.

(d) Both the visual and auditory cortices need normal experience early in life to develop normal sensitivities.

Question 5

What is one way in which the auditory and visual cortices differ?

Answer 5

Damage to the primary visual cortex leaves someone blind, but damage to the pri- mary auditory cortex merely impairs perception of complex sounds without making the person deaf

Question 6

What evidence suggests that human concepts rely on activation
of the relevant sensory or motor areas of the cortex?

Answer 6

People with damage to the auditory cortex regard many sound-related words, such as “thunder,” as if they were nonwords

Question 7

Which method of sound localization is more effective for an animal with a small head? Which is more effective for an ani- mal with a large head? Why?

Answer 7

An animal with a small head localizes sounds mainly by differences in loudness because the ears are not far enough apart for differences in onset time to be useful. An animal with a large head localizes sounds mainly by differences in onset time because its ears are far apart and well suited to noting differences in phase or onset time.

Question 8

What evidence suggests that absolute pitch depends on special experiences?

Answer 8

Forekommer nesten kun hos musikkere som har spilt siden de var små. Samt personer fra vietnam og kine der språk bygger på vokale tonehøyder

Question 9

Where are the auditory receptors, known as hair cells?

Answer 9

Along the basilar membrane of the cochlea

Question 10

What is meant by a “tonotopic map”?

Answer 10

Each location in the auditory cortex responds to a prefered tone

Question 11

What type of sound do we localize by comparing the time of arrival at the two ears?

Answer 11

Sudden sounds

Question 12

Why do many older people have trouble understanding speech despite using hearing aids?

Answer 12

Lack of inhibitory transmission in the auditory cortex C. Decrease in social responsiveness