Top-down gain control in the auditory system: evidence from identification and discrimination experiments

Area of Science:

• Auditory Perception
• Psychoacoustics
• Sensory Neuroscience

Background:

• The influence of stimulus intensity range on auditory identification and discrimination is typically attributed to nonsensory factors.
• Recent research suggests that stimulus range effects may have a sensory basis.

Purpose of the Study:

• To investigate the sensory origin of stimulus range effects in auditory perception.
• To explore the asymmetrical range effect and its implications for auditory processing.

Main Methods:

• Listeners performed auditory identification tasks with varying tone sets (intensity and frequency).
• Experiments included baseline conditions, augmented tone sets, and intensity discrimination tasks.
• A signal-detection model with Laplace distributions was used to analyze identification data.

Main Results:

• Adding a 5-kHz tone had minimal impact on identifying 1-kHz tones.
• Adding a 1-kHz tone significantly impaired identification accuracy, especially when intensity differed greatly.
• A high-intensity tone added to a low-intensity set was more detrimental than the reverse, indicating an asymmetrical range effect.

Conclusions:

• Auditory range effects appear to be sensory in origin, possibly mediated by a top-down controlled nonlinear amplifier.
• This mechanism may serve to protect the auditory system from sensory overload by loud sounds.
• The findings support the use of Laplace distributions over Gaussian distributions in signal-detection models for auditory identification.