One sound or two? Object-related negativity indexes echo perception.

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Cognitive Psychology

Background:

• Auditory perception requires isolating sound sources amidst reverberation.
• The precedence effect demonstrates how brief delays cause listeners to perceive a single sound source.
• Both low-level neural mechanisms and top-down cognitive processes influence echo perception.

Purpose of the Study:

• To investigate the neural mechanisms underlying the perception of auditory objects.
• To determine if cognitive processes influence the neural correlates of the precedence effect.
• To identify a specific neural marker for the conscious perception of separate sound sources.

Main Methods:

• Event-related potentials (ERPs) were recorded in human listeners.
• Stimuli consisted of click pairs presented with varying onset asynchronies around the echo threshold.
• Listeners reported their perception of hearing one or two sound sources.

Main Results:

• A distinct negativity between 100 and 250 milliseconds, termed the object-related negativity (ORN), was observed.
• The ORN was present when listeners perceived two distinct sound sources, even with identical stimuli.
• The presence of the ORN correlated with the conscious perception of a second sound source.

Conclusions:

• The object-related negativity (ORN) represents a neural mechanism for conscious auditory object perception.
• Cognitive factors significantly shape the perception of auditory events, including simulated echoes.
• This research provides a neural basis for understanding how the brain segregates concurrent auditory information.