Contextual Lateralization Based on Interaural Level Differences Is Preshaped by the Auditory Periphery and...

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Computational Auditory Neuroscience

Background:

• Sound localization relies on interaural time and level differences (ITD and ILD).
• Precursor sounds can significantly influence the perceived location of a target sound.
• Interaural level difference (ILD)-based precursor effects (PEs) are crucial for understanding auditory scene analysis.

Purpose of the Study:

• To characterize ILD-based PEs for high-frequency sounds in normal-hearing listeners.
• To investigate the role of the auditory periphery in shaping these PEs.
• To examine the influence of sequential segregation on ILD-based PEs.

Main Methods:

• Seven normal-hearing listeners performed a head-pointing task to measure perceived target azimuth.
• Band-pass filtered noises centered at 4 kHz were used as precursors and targets with a 10-ms gap.
• Experiments varied precursor location (ipsilateral, contralateral, central) and introduced pitch differences for sequential segregation.

Main Results:

• Ipsilateral precursors caused a medial bias, contralateral precursors a lateral bias, and central precursors a symmetric lateral bias.
• An auditory periphery model explained approximately 50% of the variance in within-trial PEs.
• Sequential segregation modulated PEs, with ipsilateral PEs increasing and central PEs decreasing or showing no change.

Conclusions:

• ILD-based within-trial PEs are significantly shaped by auditory periphery processing.
• The mechanism for ipsilateral PEs appears resistant to sequential segregation effects.
• These findings provide insights into the neural basis of auditory spatial perception and scene analysis.