Restoring Perceived Loudness for Listeners With Hearing Loss

Area of Science:

• Audiology
• Hearing Science
• Signal Processing

Background:

• Hearing aids aim to normalize loudness perception, but standard gains can cause over-amplification, especially with broadband signals.
• Monaural narrowband loudness functions may not accurately predict binaural broadband loudness needs for hearing aid users.

Purpose of the Study:

• To introduce and evaluate a binaural bandwidth-adaptive dynamic compressor (BBDC) for hearing aids.
• To test the hypothesis that the BBDC can restore normal perceived loudness across various signals for individuals with high-frequency hearing loss.

Main Methods:

• Assessed loudness functions in 15 listeners with mild-to-moderate high-frequency hearing loss using categorical loudness scaling.
• Developed and applied a BBDC with signal-dependent gain adjustments for narrow- and broadband signals.
• Compared BBDC gains to the NAL-NL2 fitting procedure and evaluated perceived loudness for real-world signals.

Main Results:

• The BBDC achieved near-normal loudness functions for both narrowband and broadband signals in listeners with hearing loss.
• Perceived loudness ratings for real-world signals were normalized with the BBDC.
• While average gains resembled NAL-NL2, significant interindividual differences in broadband gain corrections were observed.

Conclusions:

• Binaural broadband measurements are crucial for accurate loudness normalization, as monaural narrowband data is insufficient.
• The BBDC effectively avoids over-amplification by incorporating individual binaural broadband gain corrections.
• The BBDC offers a more appropriate approach to loudness compensation than traditional threshold-based methods for diverse signal bandwidths.