How is sound localized by the ear?

Sound localization is the process by which the ear determines the location of sound source. This process utilizes: subtle of difference in

• intensity
• spectral
• timing cues

 

Localization can be described in terms of 3^rd dimensional position.

 

1. The azimuth/horizontal angel
   • Difference in arrival time between the ears, interval time difference.
   • Relative amptitue of high frequency sound ( the head shadow effect )
   • By asymmetrical spectral reflection from varous part of our bodies, including torso, shouldiers and pinno.
   • Sound from right reaches the right ear first than the left ear because head shadows the left ear.

 

2. The elevation/vertical angle
   • Monaural of the pinna and EAC from direction selective filters.
   • Dynamic binaural cues localization during head rotation.
   • Interval time difference
   • Interval level difference
   • Cocktail party effect.

 

3. Distance Velocity

It uses these clues to estimate the distance to the sound source

1. Direct/reflection ratio
2. Loudness : Distance & loudness
3. Sound spectrum: Distance sound source sounds more muffled than close one because high frequencies are alternated.
4. Initial time delay are small because the direct and the reflected sound waves have similar length.
5. For a moving listener nearby sound source are passing faster than distant source.
6. Level Difference: Very close sound source causes a different level b/w ears.

Tags: COCKTAIL PARTY EFFECT, Ear, ENT, HEARING, HOW IS SOUND LOCALIZED BY EAR, LOCALIZATION OF SOUND, MBBS QUESTION, MS ENT QUESTIONS, Sound