Potential Destructive Binaural Interaction Effects in Auditory Steady-State Response Measurements

Area of Science:

• Audiology
• Neuroscience
• Biomedical Engineering

Background:

• Auditory steady-state response (ASSR) is a potential objective measure for validating hearing aid (HA) fittings.
• Independent ear testing is ideal, but binaural testing might be used to save time.

Purpose of the Study:

• To investigate the risk of false judgments in aided sound-field ASSR testing due to binaural effects.
• To simulate dichotic ASSR conditions and assess their impact on HA fitting validation.

Main Methods:

• Recorded unaided ASSRs in 15 normal-hearing subjects using a clinical two-channel electroencephalography (EEG) system.
• Utilized a three-band CE-Chirp® stimulus and simulated dichotic sound-field conditions with interaural time differences.

Main Results:

• Large interaural time differences (half stimulus envelope period) suppressed response power by up to 10 dB.
• Altered ASSR topographies and reduced measured response power were observed, potentially leading to false referrals.
• Simulated stimulus lateralizations did not affect results, supporting the proposed aided ASSR approach.

Conclusions:

• Unchecked binaural effects in ASSR testing can lead to misinterpretations of hearing aid fitting success.
• Monaural ASSR testing is recommended to avoid false referrals caused by binaural interference.
• The findings highlight the importance of considering binaural interactions in objective audiological assessments.