Lecture 19

Question 1

Describe neural frequency tuning curves

Answer 1

Pure tones can be used to determine the threshold for specific frequencies
measured at single neurons, which can then be used to produce neural
frequency tuning curves

Question 2

Describe characteristic frequency

Answer 2

Frequency to which the neuron is most
sensitive

Question 3

Describe the cochlear amplifier

Answer 3

the entire outer hair cells
respond to sound by slight tilting and a
change in length
* These cells are referred to as the
cochlear amplifier

Question 4

Describe the importance of cochlear amplifiers

Answer 4

• Damage to the outer hair cells impacts
  the frequency tuning curve,
  demonstrating the role they play when
  intact
• Higher threshold = lower sensitivity =
  worse hearing

Question 5

Describe place theory

Answer 5

Place theory suggests that pitch perception is based on the relation between
a sound’s frequency and the place along the basilar membrane that is
activated

Question 6

Describe the effect of the missing fundamental

Answer 6

The ‘effect of the missing fundamental’
could be explained by assuming the
harmonics also vibrate the membrane, and
that the spacing of the intervals is
informative of the fundamental

Question 7

Describe resolved harmonics

Answer 7

The lower harmonics produced by tones
tend to create distinct neural responses

Question 8

What are unresolved harmonics?

Answer 8

In contrast, higher harmonics tend to create
neural responses that are not clearly
distinguishable

Question 9

What is another name for the repetition rate?

Answer 9

the interval spacing

Question 10

Describe phase locking

Answer 10

carries similar temporal information that may assist
with pitch perception

Question 11

Name the places that the auditory nerve signal travels to

Answer 11

• The auditory nerve sends signals generated
  in the cochlea to various subcortical
  structures while en route to primary auditory
  cortex, including:
• Cochlear nucleus
• Superior olivary nucleus (brain stem)
• Inferior colliculus (midbrain)
• Medial geniculate nucleus (thalamus)
• Acronym: SONIC MG

Question 12

Describe the primary auditory cortex

Answer 12

(auditory
receiving area, or A1, in temporal
lobe) can be divided up into three
general subregions:
* Core area
* Belt area
* Parabelt area

Question 13

Describe pitch neurons

Answer 13

respond to the same fundamental frequency,
regardless of what harmonic is heard

Question 14

Describe anterior auditory cortex

Answer 14

Evidence for a greater responses to pitch information

Question 15

Describe noise induced hearing loss

Answer 15

Acute
exposure to very loud noises can severely
damage the hair cells in the organ of Corti

Question 16

Describe hidden hearing loss

Answer 16

situations in which individuals may have normal results
(e.g. thresholds) in a standard hearing test using pure tones played in isolation, yet
have difficulty perceiving more complex ‘real-word’ sounds

Question 17

Describe presbycusis

Answer 17

Results from the cumulative effects of exposure to noise over time

• Greatest loss at high frequencies
• Affects males more severely than females
• Can be caused by exposure to some drugs (which damage the hair cells)

Question 18

Describe auditory localization

Answer 18

• Locating sounds in space

Question 19

Describe azimuth coordinates

Answer 19

left to right position

Question 20

Describe elevation coordinates

Answer 20

up and down position

Question 21

Describe distance coordinates

Answer 21

position relative to observer

Question 22

Describe location cues

Answer 22

created based on how sound waves interact with our
head/ears

Question 23

Describe binaural cues

Answer 23

location cues based on the comparison of the signals
received by the left and right ears (interaural time and level differences) to
determine the azimuth (i.e. left-right) position of sounds

Question 24

Describe interaural level difference

Answer 24

a binaural cue related to differences in
sound pressure levels reaching each ear

Question 25

Describe acoustic shadows

Answer 25

• Reduction in intensity occurs for high frequency sounds for the far (relative to
  audio source) ear, due to the head casting an acoustic shadow
• This effect does not occur for low frequency sounds
  because the distance, or spacing, between waves
  (i.e. frequency) for low frequency sounds is relatively
  large, in comparison to the object casting the
  acoustic shadow (i.e. your head)

Question 26

Describe intraural time difference

Answer 26

a binaural cue
related to differences in the timing of when a sound
reaches each ear
* When distance to each ear is the same, there is no
difference in timing (ITD = 0)
* When the source is to the side of the observer, the
times will differ
* Behavioural experiments show that ITD is most
effective for localizing low frequency sounds

Question 27

Describe cone of confusion

Answer 27

(many) conical
space(s) around the ears for which various
possible pairs of points on an ‘imaginary cone’
would produce the same ITD and ILD

Question 28

Describe monaural cues

Answer 28

location cues based on signals reaching a single ear

Question 29

Describe spectral cues

Answer 29

The monaural cue we primarily rely on is referred to as a spectral cue, because it
involve using information related to the distribution of intensities of a particular
spectrum of frequencies experienced

Question 30

Describe frequency spectra study

Answer 30

Frequency spectra recorded by a microphone placed inside the ear for the
same stimulus being played at different elevations