Population rate-coding predicts correctly that human sound localization depends on sound intensity.

Area of Science:

• Neuroscience
• Auditory Perception
• Computational Neuroscience

Background:

• Sound localization is a crucial brain function.
• Current models often assume sound lateralization is level-invariant.
• Two models, labelled-line and hemispheric-difference, offer contrasting predictions.

Purpose of the Study:

• To investigate the level-invariance of sound localization based on interaural time differences.
• To differentiate between the predictions of labelled-line and hemispheric-difference models.
• To explore potential parallels between auditory and visual spatial perception computations.

Main Methods:

• Behavioral experiments measuring perceived sound direction at varying sound levels.
• Comparison of experimental results with predictions from two distinct computational models.
• Analysis of the relationship between sound level and perceived laterality.

Main Results:

• Softer sounds were perceived closer to the midline compared to louder sounds.
• These findings contradict the level-invariance prediction of the labelled-line model.
• Results favor models that incorporate sound level-dependent rate-coding for spatial representation.

Conclusions:

• Human sound localization, specifically lateralization, is influenced by sound intensity.
• Rate-coding mechanisms appear more critical than previously assumed for auditory spatial perception.
• The brain may employ a unified computational strategy for spatial encoding across sensory modalities, relying on population spike rates.