Attribute capture in the precedence effect for long-duration noise sounds.

Area of Science:

• Auditory perception
• Psychoacoustics
• Neuroscience

Background:

• The precedence effect describes how listeners fuse direct sound waves with their reflections, localizing the perceived sound near the source.
• Understanding how auditory systems process changes within these fused sound waves is crucial for explaining auditory scene analysis.

Purpose of the Study:

• To investigate the perceptual incorporation of brief gaps within direct or reflected sound waves during auditory fusion.
• To determine how these gaps influence the perceived location and characteristics of the fused sound image.

Main Methods:

• Manipulating the timing and location of brief gaps within direct (leading) and simulated reflected (lagging) sound waves.
• Assessing listener perception of the fused sound image and the location of the perceived gap.
• Measuring scalp event-related potentials (ERPs) to identify neural correlates of auditory fusion and gap perception.

Main Results:

• For short delays (<9.5 ms), gaps in either the direct or reflected wave were perceived as belonging to the leading sound.
• At longer delays (10–15 ms), gaps were perceived on the leading side, and gap detection thresholds remained consistent regardless of whether the gap was in the leading or lagging sound.
• Scalp event-related potentials related to the precedence effect emerged only after the gap occurred, suggesting neural engagement for maintaining fusion.

Conclusions:

• The auditory system incorporates gaps within reflected sound waves into the leading sound, demonstrating robust auditory fusion.
• Perceptual suppression of the lagging wave at short delays is overcome by gap introduction, with perception favoring the leading sound.
• Cortical mechanisms are actively engaged to maintain auditory fusion when changes occur in direct or reflected sound wave attributes.