Audition

Question 1

What is place theory

Answer 1

• our perception of sound depends on where the frequency (location of maximum displacement) produces vibrations along the basilar membrane
• each position of the basilar membrane is associated with a particular frequency

Question 2

How is the frequency mapped in the ear according to the place theory?

Answer 2

-the mapping of place is linearly related to frequency with frequency gradually decreasing as one moves from the oval window (base) to the apex of teh cohlea

Question 3

According to place theory, at the base (oval window) what frequencies does it respond to and what bandwidth does it have?

Answer 3

high and sharp frequencies

small bandwidth - only lets good sounds in

Question 4

According to place theory, at the apex what frequencies does it respond to and what bandwidth does it have?

Answer 4

low and not sharp frequencies

large bandwidth

Question 5

What is place coding (a concept within place theory)

Answer 5

-pitch discrimination for pure tones should depend on the bandwidth of audio filters

Question 6

What are the problems with place theory?

Answer 6

• cannot fully account for our ability to discriminate between two tones of similar frequencies
• cant account for the missing fundamental

Question 7

How do we measure auditory filter bandwidth?

Answer 7

• using masking experiments

- the perception of one sound is affected by the presence of another

Question 8

what is a critical bandwidth (a concept within place theory)

Answer 8

the smallest band of frequencies around it which will activate the same part of the basilar membrane

Question 9

what is frequency selectivity

Answer 9

if two sounds of two different frequencies are played together two separate sounds can often be heard rather than a combination tone

Question 10

what is the missing fundamental

Answer 10

pitch is perceived also by the relationships between harmonics, sometimes the fundamental may not even be present but we can still hear it

Question 11

What is timing theory

Answer 11

says that our perception of sound depends on the timing patterns to which the neurons respond to sound in cochlea

Question 12

What is phase-locking (a concept within timing theory?)

Answer 12

the chemical process is timed with how the auditory nerve fires. The principle only works for low frequencies (up to 4 hz) because of the refractory period

Question 13

What is the volley principle and what does it explain

Answer 13

• it explains how we hear pitches with frequencies higher than 4 Hz
• it explains the perception of pure tones and the missing fundamental
• the summation of different responses for each fibre codes the sound for higher frequencies

Question 14

Discuss how the timing theory explains the missing fundamental

Answer 14

• the two harmonics of the higher frequencies fit into the same bandwidth (unresolved harmonics)
• the unresolved harmonics produce beats which helps you perceive the missing fundamental called “residue pitch”

Question 15

What is a problem with the timing theory

Answer 15

-you don’t hear the pitch for unresolved harmonics when they say you should

Question 16

What is pattern theory

Answer 16

• the brain resolves individual sine wave components and analyses frequencies using place code
• it then finds the best firing harmonic series that sound like the fundamental frequency

Question 17

What can the pattern theory account for?

Answer 17

• the missing fundamental

- for reliance on resolved harmonics

Question 18

What is a problem for the pattern theory?

Answer 18

-it cannot explain residue pitch for unresolved harmonics