Right hemispheric dominance for echo suppression.

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Cognitive Neuroscience

Background:

• The precedence effect (PE) describes the perception of a single auditory event when two sounds are presented sequentially with a short delay.
• The perceived location is primarily determined by the leading sound's directional information.
• PE can build up over repetitions, suggesting dynamic neural processes.

Purpose of the Study:

• To investigate how lateralization cues (interaural time differences - ITD, and interaural intensity differences - IID) and the leading sound's lateralization affect the spatio-temporal neural activity underlying the PE.
• To compare auditory evoked potentials (AEPs) for fused versus segregated auditory perceptions.

Main Methods:

• Electrical neuroimaging analyses were used to examine AEPs.
• Physically identical click pairs were presented early and late in a stimulus train.
• Stimuli varied in lateralization cues (ITD/IID) and leading sound side.

Main Results:

• Significant topographic AEP modulations (70-117ms post-stimulus) distinguished fused from segregated perceptions.
• PE build-up occurred for ITD stimuli regardless of leading sound lateralization.
• IID stimuli showed no build-up but were affected by leading sound lateralization.
• Source estimations indicated bilateral temporal networks for segregated perceptions and altered left/right cortical activity for fused perceptions.

Conclusions:

• The neural basis of the precedence effect is modulated by the type of lateralization cue and the leading sound's spatial information.
• Distinct spatio-temporal brain activity patterns differentiate fused and segregated auditory event perception.
• The findings shed light on the neural mechanisms of auditory scene analysis and spatial hearing.