A precedence effect in the perception of inter-aural cross correlation

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Binaural Hearing

Background:

• The precedence effect is a well-established phenomenon in auditory perception, primarily studied in the context of sound localization and lateralization.
• This effect describes the dominance of the earliest arriving sound cues in determining the perceived location of a sound source.

Purpose of the Study:

• To investigate whether the precedence effect extends to other auditory percepts beyond sound localization, specifically the perception of sound image diffuseness or compactness.
• To compare the influence of inter-aural time delay (IATD) and inter-aural cross correlation (IACC) on the precedence effect within a unified experimental framework.

Main Methods:

• Utilized dichotic headphone stimulation with a 20-ms noise burst, divided into two 10-ms parts.
• Manipulated inter-aural time delay (IATD) to control lateralization and inter-aural cross correlation (IACC) to control sound diffuseness/compactness.
• Assessed the overall auditory sensation when dichotic information in the leading part was opposite to that in the trailing part.

Main Results:

• The leading part of the noise burst exerted a slight dominance over the overall auditory sensation for both lateralization (IATD) and compactness/diffuseness (IACC).
• This leading-part dominance could be counteracted by reducing the duration or amplitude of the initial segment relative to the trailing segment.
• The quantitative strength of this precedence effect was found to be similar for both IATD and IACC.

Conclusions:

• The findings suggest that the precedence effect is not limited to sound localization but also applies to other binaural processing percepts, such as the perception of sound image diffuseness/compactness.
• This indicates a broader role for the precedence effect in auditory perception, encompassing the processing of inter-aural cross correlation.