What is sound localization?
Sound localization is our ability to locate where a sound source is coming from.
Directions/planes of sound:
Acoustic cues used for localizing sounds are:
Interaural time differences (ITD):
Interaural level differences (ILD):
Does the loss of OHCs affect sound localization?
The loss of OHCs does not affect sound localization if there is OHC loss in both ears. However, if there is hearing loss in one ear, ITD and ILD could be affected.
Sound localization is our ability to locate where a sound source is coming from.
Directions/planes of sound:
- Azimuth: This refers to the horizontal (left and right of head) plane. Localization in azimuth is best when the sound source is straight ahead of us.
- Elevation: This refers to the vertical (looking up and looking down) plane. We are not as good at localizing sounds above or below us.
- Distance: This refers to how close or far away the sound source is from us. We underestimate how far a sound is, to give ourselves ample warning time in case of danger.
Acoustic cues used for localizing sounds are:
- Interaural Time Difference: This refers to the difference in time it takes for the sound to reach one ear vs. the other. For example, if a sound source is coming from the right side of your head, then it would reach your right ear a lot quicker than it would reach your left ear.
- Interaural Level Difference: This refers to the difference in level of the sound that reaches one ear vs. the other. For example, if the sound is coming from your left side, then it would be a higher level in the left ear than it would be in the right ear.
- Spectral Cues of the Pinna: This refers to the collection of frequencies by the pinna. This acoustic cue is most helpful in elevation.
Interaural time differences (ITD):
- When the distance of a sound is the same to both ears, there will be no differences in arrival time. For example, when the sound is directly in front of you on the azimuth (horizontal) plane, the ITD is zero. In contrast, if a sound coming from the side of your head, you would experience a difference in arrival time. ITD is useful for the localization of sounds with low-frequencies more than it is for high frequencies.
Interaural level differences (ILD):
- Head shadowing: when a sound is presented to one side of the head, this creates a "shadowing" effect, which prevents some of the energy of that sound to reach the other side of the head. ILDs provide reliable location information for sounds in the azimuth (horizontal) plane.
Does the loss of OHCs affect sound localization?
The loss of OHCs does not affect sound localization if there is OHC loss in both ears. However, if there is hearing loss in one ear, ITD and ILD could be affected.