problem 7 - hearing & listening

Question 1

auditory localization

Answer 1

locating objects in space based on their sound

3 dimensions:
1. The azimuth: extends from left to right
2. Elevation: extends from up & down
3. The distance of the sounds source from the listener

Question 2

binaural cues

Answer 2

• uses both ears
• based on a comparison of the sound signals reaching the left and right ears

interaural time difference (ITD) and interaural level difference (ILD)

Question 3

interaural time difference (ITD)

Answer 3

based on the fact that there is a difference in when a sound reaches the left and right ears

source is directly in front of the listener = distance to each ear is the same = sound reaches left and right ears simultaneously

source is located off to the side = sound reaches the right ear before it reaches the left ear

magnitude of the ITD can be used as a cue to determine a sound’s location

Question 4

interaural level difference (ILD)

Answer 4

based on the difference in the pressure level of the sound reaching the two ears

A difference in level between the two ears occurs because the head creates a barrier that reduces the intensity of sounds that reach the far ear

Occurs for high-frequency sounds, but not for low-frequency sounds - because high freq waves are small compared to head so get disrupted

acoustic shadow

Question 5

monaural cues

Answer 5

depends on info from only one ear - provides info that binaural cues cannot

Question 6

spectral cues

Answer 6

the primary monaural cue

the info for localization is contained in differences in the distribution (or spectrum) of frequencies that reach the ear from different locations

differences are caused by the fact that before the sound stimulus enters the auditory canal, it is reflected from the head and within the various folds of the pinnae

Question 7

directional transfer function

Answer 7

The difference between the original sound and the sound that reaches the ear

The higher the frequency the more prominent the DFT will be

Question 8

how the pinnae helps with hearing

Answer 8

very important for determining elevation - imp has been demonstrated by smoothing out the nooks and crannies of the pinnae with molding compound → makes it difficult to locate sounds along the elevation coordinate (hofman et al)

pinnae shape bounces the sound waves diff for diff locations –> diff patterns created in out ear –> helps to determine where sound is coming from