Auditory Numerosity Judgement Is Driven by Non-Spatial Factors Across Azimuth, Elevation, and Distance

Area of Science:

• Auditory perception
• Psychoacoustics
• Scene analysis

Background:

• Everyday listening involves processing complex acoustic scenes with multiple sound sources.
• Listeners may use summary representations rather than object-based parsing for many simultaneous sounds.
• Auditory numerosity judgement offers insight into perceiving complex sound environments.

Purpose of the Study:

• To investigate how listeners judge the number of sound sources in complex acoustic scenes.
• To dissociate spatial and non-spatial factors influencing auditory numerosity perception.
• To determine if spatial hearing precision or acoustic mixture properties modulate numerosity judgements.

Main Methods:

• Numerosity judgements were measured across azimuth, elevation, and distance dimensions of auditory space.
• Spatial hearing performance and speech intelligibility were assessed.
• The influence of spectrotemporal coverage of the acoustic mixture was analyzed.

Main Results:

• Auditory numerosity judgements were not systematically related to individual spatial hearing performance.
• Speech intelligibility had a minimal impact on numerosity judgements.
• Perceived numerosity was significantly influenced by the spectrotemporal coverage of the acoustic mixture.

Conclusions:

• Auditory numerosity perception is largely independent of spatial hearing precision.
• The perception of sound quantity in complex scenes relies on general acoustic mixture properties.
• Findings suggest scene-level processing principles govern auditory numerosity.