How is sound localized in the horizontal plane?

How is sound localized in the horizontal plane?

• A. By ear canal resonance
• B. By reflexive head-turn
• C. By processing in the medullary nuclei of the auditory system
• D. By cochlear hair cell tuning

Answer: (C)

Sound localization in the horizontal plane depends on binaural cues—the differences in how a sound arrives at each ear. The brainstem houses the nuclei that extract and compare these cues, converting timing and level differences into a spatial map of left-right position. This processing primarily occurs in medullary auditory nuclei, where neurons act as coincidence detectors and level-difference analyzers to compute where a sound is coming from along the azimuth. Ear canal resonance mainly affects the spectral content of sounds but doesn’t provide precise horizontal localization. A reflexive head-turn is a behavioral response to sound, not the neural mechanism that determines direction. Cochlear hair cell tuning relates to frequency selectivity at the cochlea, not to comparing inputs from both ears for azimuth localization.

Sound localization in the horizontal plane depends on binaural cues—the differences in how a sound arrives at each ear. The brainstem houses the nuclei that extract and compare these cues, converting timing and level differences into a spatial map of left-right position. This processing primarily occurs in medullary auditory nuclei, where neurons act as coincidence detectors and level-difference analyzers to compute where a sound is coming from along the azimuth.

Ear canal resonance mainly affects the spectral content of sounds but doesn’t provide precise horizontal localization. A reflexive head-turn is a behavioral response to sound, not the neural mechanism that determines direction. Cochlear hair cell tuning relates to frequency selectivity at the cochlea, not to comparing inputs from both ears for azimuth localization.