The psychophysical basis of monaural localization

Area of Science:

• Auditory Neuroscience
• Acoustics
• Psychoacoustics

Background:

• Sound localization is crucial for auditory perception and spatial awareness.
• The pinna, the outer part of the ear, plays a significant role in filtering and amplifying sound based on its direction.
• Understanding the relationship between pinna-induced spectral cues and perceived sound location is vital for auditory research.

Purpose of the Study:

• To investigate how the pinna's frequency-dependent amplification influences sound localization in the horizontal plane.
• To determine if spectral cues, shaped by the pinna, are the primary drivers of sound source judgments.

Main Methods:

• Listeners performed monaural sound localization of noise bursts across a 180-degree azimuth range.
• Stimuli varied in center frequency (4.0-14.0 kHz) and bandwidth (1.0 kHz).
• The pinna's relative amplification for each stimulus was measured using a miniature microphone at the ear canal entrance.

Main Results:

• Location judgments were strongly correlated with the frequency composition of the stimuli.
• The loudspeaker position associated with the greatest pinna amplification for a given noise burst was most frequently chosen as the source.
• This suggests spectral modifications by the pinna are key to sound localization.

Conclusions:

• The pinna's spectral filtering significantly impacts sound localization accuracy.
• Frequency composition, as modified by the pinna, is a primary cue for determining sound source location in the horizontal plane.
• These findings contribute to models of auditory spatial processing.