Detection of middle-ear muscle reflex activation using changes in otoacoustic emission stimulus amplitude versus absorbance: an initial investigation

Abstract Objectives The medial olivocochlear reflex (MOCR) reduces cochlear amplifier gain, which may be beneficial for hearing in noise. Additionally, measurement of the MOCR may be diagnostically useful in the audiology clinic. The MOCR can be measured as the change in transient-evoked otoacoustic emission (TEOAE) amplitude without versus with contralateral acoustic stimulation (CAS). However, CAS can activate the middle-ear muscle reflex (MEMR) which can confound the MOCR results. MEMR activation has been assessed using changes in TEOAE stimulus amplitude without versus with CAS. As an initial investigation, the current study compared detection of MEMR activation using changes in TEOAE stimulus amplitude to changes in wideband absorbance. Methods In 26 normal-hearing participants, the MEMR was measured as the change in absorbance and as the change in TEOAE stimulus amplitude without and with CAS. Percentile critical differences were developed from the test-retest measurements. Measures of agreement between MEMR detection methods were computed. Results CAS resulted in a larger number of participants exceeding the 95th percentile critical difference for absorbance compared to TEOAE stimulus amplitude (22 versus 1). Agreement between methods was low. Conclusion Initial results indicated that MEMR was detectable in a larger number of participants when using absorbance compared to TEOAE stimulus amplitude. However, future work could better equate the two methods and include measurement of MEMR thresholds to determine optimal methods for detecting MEMR activation during MOCR assessments.