Comparison between adaptive and adjustment procedures for binaural loudness balancing.

Area of Science:

• Audiology
• Hearing Science
• Psychoacoustics

Background:

• Binaural loudness balancing is essential for fitting bilateral hearing devices.
• It is particularly critical for bimodal listeners using a hearing aid and cochlear implant combination.
• Accurate loudness balancing ensures optimal audibility and speech understanding with hearing devices.

Purpose of the Study:

• To compare two psychophysical binaural loudness balancing procedures: adaptive and adjustment.
• To investigate the effect of procedure type and starting level on balanced loudness levels.
• To determine the most reliable method for loudness balancing in simulated bimodal hearing conditions.

Main Methods:

• Two experiments were conducted with normal-hearing volunteers.
• Experiment 1 compared adaptive and adjustment procedures using noise band stimuli with frequency shifts.
• Experiment 2 investigated the effect of starting levels in the adjustment procedure and compared it with the adaptive method across different reference levels and carrier frequencies.

Main Results:

• Both procedures yielded similar averaged balanced loudness levels.
• The adjustment procedure demonstrated smaller standard deviations across test sessions, indicating higher reliability.
• Experiment 2 results suggested conducting the adjustment procedure twice, from below and above the target level, to avoid bias.

Conclusions:

• The adjustment procedure is more reliable for binaural loudness balancing than the adaptive procedure.
• To minimize bias, the adjustment procedure should be performed from both lower and higher starting levels.
• These findings can refine clinical practices for fitting bilateral hearing devices, especially for bimodal listeners.