Estimates of human cochlear tuning at low levels using forward and simultaneous masking

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Human Hearing

Background:

• Understanding auditory filter shapes is crucial for modeling human cochlear processing.
• Previous estimates of auditory filter bandwidths, primarily from simultaneous masking, may not accurately reflect low-level cochlear tuning.

Purpose of the Study:

• To derive auditory filter shapes using psychophysical measurements in normal-hearing listeners.
• To compare auditory filter bandwidths under forward and simultaneous masking conditions.
• To provide more accurate estimates of human cochlear tuning suitable for cross-species comparison.

Main Methods:

• Psychophysical measurements using a notched-noise method with brief signals.
• Testing signal frequencies from 1 to 8 kHz.
• Employing both forward and simultaneous masking at controlled signal levels (10 and 35 dB above threshold).

Main Results:

• Equivalent Rectangular Bandwidths (ERBs) were substantially narrower in forward masking compared to simultaneous masking.
• Auditory filter sharpness (Q(ERB)) doubled across the tested frequency range (1-8 kHz), reaching values of approximately 10 and 20.
• New estimates suggest narrower bandwidths and sharper tuning at low signal levels.

Conclusions:

• Forward masking provides a more accurate representation of human cochlear tuning at low signal levels than previous simultaneous masking estimates.
• The findings offer improved data for comparing human cochlear tuning with that of other species.
• The results can inform the development of nonlinear models of cochlear processing.