Auditory localization in a free field using discrimination procedures

Area of Science:

• Auditory perception
• Psychoacoustics
• Human spatial orientation

Background:

• Accurate sound localization is crucial for environmental awareness and interaction.
• Previous research established minimum audible angles (MAA) under various conditions.
• The impact of masking noise and specific testing paradigms on spatial discrimination requires further investigation.

Purpose of the Study:

• To determine the minimum discriminable angle (MDA) for sound source azimuth.
• To evaluate the effect of masking noise on auditory spatial resolution.
• To compare MDA results with existing literature on minimum audible angles (MAA).

Main Methods:

• Participants (N=3) were presented with 750-ms bursts of pink noise at 54 dB SPL in an anechoic chamber.
• A loudspeaker moved in clockwise or counterclockwise directions during a masking noise (73 dB SPL).
• Participants judged if the sound source azimuth changed, with MDA calculated at a 70% correct rate.

Main Results:

• Minimum discriminable angles (MDAs) were smallest at 0 degrees azimuth (approx. 4.5 degrees) and largest in the rear quadrants.
• Localization performance was relatively good at 180 degrees azimuth (approx. 8.5 degrees).
• One participant demonstrated exceptional performance with a low false alarm rate.

Conclusions:

• Auditory spatial discrimination is generally poorer in the rear hemifield compared to the front.
• The presence of masking noise and specific experimental design may contribute to larger MDAs than previously reported MAAs.
• The study did not replicate findings of a large determination at 90 degrees azimuth reported by Mills (1958).