Simulating psychophysical tuning curves in listeners with dead regions

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Computational Auditory Modeling

Background:

• Accurate diagnosis of cochlear dead regions is crucial for understanding hearing impairment.
• Psychophysical tuning curves (PTCs) are used to identify these dead regions.
• The influence of specific cochlear pathologies on PTC-based diagnosis requires further elucidation.

Purpose of the Study:

• To investigate the relationship between dead region diagnosis using the off-frequency psychophysical tuning curve (PTC) tip and probe tone characteristics.
• To evaluate the impact of simulated inner hair cell (IHC) and outer hair cell (OHC) dysfunction on PTCs.

Main Methods:

• A functional auditory processing model simulated various conditions: complete IHC loss, OHC dysfunction, combined IHC/OHC issues, and IHC insensitivity.
• Model predictions were validated against experimental data.
• PTC data from normal-hearing and hearing-impaired listeners were compared with model-simulated data.

Main Results:

• Outer hair cell (OHC) activity and inner hair cell (IHC) insensitivity were found to significantly affect the shift in PTC tips as probe level increased.
• Simulated OHC dysfunction and IHC insensitivity altered the diagnostic outcomes derived from PTCs.

Conclusions:

• OHC activity and IHC insensitivity can modify the diagnosis of dead regions using PTCs.
• Model results provide supplementary information for dead region diagnosis, including edge frequency and OHC function assessment.
• This study highlights the importance of considering cochlear function when interpreting PTC data.