Hearing

Question 1

What is the law of specific nerve energies?

Answer 1

Muller - The neural pathway carrying the signal determines the sensation

Question 2

What are the 2 theories of pitch reception?

Answer 2

• Place code theory (Helmholtz)

- Temporal code theory (Wever)

Question 3

Describe the place code theory

Answer 3

• Specific pitch causes a specific place in the cochlear membrane to vibrate
• Specific auditory nerves carry the information code of the pitch
• Vibrations are of the same frequency with different oscillation sizes

Question 4

What is the cochlear microphonic?

Answer 4

• small electrical signal that can be measured near hair cells
• Frequency of tones correlate to firing rate

Question 5

What is the problem with the temporal code theory?

Answer 5

That while nerve firing rate can only go up to 1000Hz we can hear a range of 20-20000 Hz

Question 6

What is the volley principle?

Answer 6

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

Question 7

Define interaural level difference (IAL)

Answer 7

The difference in level (intensity) between a sound arriving at one ear versus the other

Question 8

Why is there a bigger difference in IAL for higher frequencies?

Answer 8

Because low frequencies are wider then the head and high frequencies have to vibrate through the head

Question 9

What are the 2 ways of detecting azimuth?

Answer 9

interaural level difference and interaural time difference

Question 10

What is the ‘cone of confusion’?

Answer 10

Regions in space where all sounds produce the same

time and level differences

Question 11

What is the function of the pinnae?

Answer 11

Shape helps determine direction of sound

Question 12

Name the 4 methods used to measure the distance of a sound

Answer 12

1. Intensity
2. Inverse-square law
3. Spectral composition
4. Direct vs reverberant energy

Question 13

What are the 3 strategies used to segregate sound sources?

Answer 13

1. Spatial separation
2. Sound spectral/temporal qualities
3. Auditory stream segregation (seperate auditory events)

Question 14

Which theories of sound coding are most used for low vs high frequencies?

Answer 14

Place coding - high frequencies

Temporal coding - low frequencies