A measure of internal noise based on sample discrimination

Area of Science:

• Auditory Perception
• Psychoacoustics
• Sensory Neuroscience

Background:

• Internal noise limits performance in sensory tasks.
• Direct measurement of internal noise is challenging.
• External variability can be manipulated to infer internal noise.

Purpose of the Study:

• To develop and validate a method for directly measuring internal noise in auditory intensity discrimination.
• To assess the reliability and accuracy of the proposed measurement technique.
• To explore the relationship between internal noise and psychometric functions.

Main Methods:

• Introduced controlled external variability (Gaussian random variable) into a two-interval forced-choice intensity discrimination task.
• Systematically varied the mean difference between stimulus levels and external noise standard deviation.
• Measured listener performance across different levels of external variability and stimulus intensities (50, 70, 90 dB SPL).

Main Results:

• The method yielded reliable estimates of internal noise.
• Internal noise measures were in good agreement with intensity difference limens (DLs) derived from psychometric functions.
• Performance limitations due to internal noise increased as external variability decreased.

Conclusions:

• The introduced method reliably quantifies internal noise in auditory intensity discrimination.
• This technique can estimate decision distribution parameters and internal noise, even when stimulus differences are unknown.
• The findings offer a valuable tool for understanding auditory processing and sensory limitations.