Objective Binaural Loudness Balancing Based on 40-Hz Auditory Steady-State Responses. Part I: Normal Hearing.
Maaike Van Eeckhoutte, Jan Wouters, Tom Francart
PMID 30334493WHAT IT FOUND
In 38 normal-hearing young adults, evoked brain responses tracked loudness balance between ears.
The predicted balance was within 5 dB of behavioral balance in 59% of cases and within 10 dB in 85%, but individual variability remained.
Key findings
01Across-ear ASSR amplitude ratios were usually near 1, but some participants showed clear deviations.
02The ASSR-predicted balanced level differed from the behaviorally balanced level by less than 5 dB in 59% of cases and by less than 10 dB in 85% of cases.
03Laterality indices were close to zero overall, with only a small right-hemisphere asymmetry at 2000 Hz for 40, 50, and 60 dB SPL.
STILL TO COME
How it was doneWhat they found
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What it does not show
Only young normal-hearing adults were tested, so it says nothing about patients with hearing loss, bimodal hearing, or people who cannot cooperate with loudness balancing. ASSR amplitudes varied between participants, and some participants showed clear deviations from equal across-ear amplitudes. The ASSR prediction differed from behavioral balance by more than 10 dB in 15% of cases. ASSR measurement took about 5 min for each condition, so a full protocol could still be lengthy. The behavioral loudness-balancing task itself can have errors, and the study compared two imperfect measures.
Declared interests
The study was funded by Agentschap voor Innovatie door Wetenschap en Technologie. The supplied text does not report additional author conflicts.
The easy way to misread this
Do not read this as a validated clinical test for balancing loudness in patients with hearing loss. The study was done in young normal-hearing adults, and the ASSR prediction differed from behavioral balance by more than 10 dB in 15% of cases.