A New Technique for Rapid Middle Ear Muscle Reflex Measurements

Abstract (English)

Middle-ear muscle reflex (MEMR) thresholds are routinely measured in the audiology clinic. Recent research has shown that MEMR thresholds are elevated in people with evidence of afferent synapse loss despite normal audiometric hearing (i.e., “hidden hearing loss”). Acoustic elicitors are classically presented in a time-consuming fashion that uses discrete steps in sound level and frequency, while a 226 Hz probe tone is used to monitor reflex activation. Clinical and research data efforts could benefit from faster data collection. Moreover, rapid measurements may be less susceptible to slow variations that putatively originate from changes such as probe placement and middle ear pressure. Here, we use our recently developed MEMR measurement paradigm that makes rapid MEMR measurements (2 min test time) with probe clicks and an elicitor noise that continuously sweeps in level. The purpose of this study was 1) to understand the retest reliability of our measurements and 2) to compare results from our paradigm with those obtained using discretely varying elicitors. Thirty young, normal-hearing participants were tested with both the continuous elicitor test (repeated four times) and the discrete elicitor test (tested once). We constructed MEMR level growth functions (LGFs) for each test from sound pressure changes in participants’ ear canals. Using total change, a measure that combines both magnitude and phase changes, LGFs were combined across frequencies from 500-1500 Hz to give a single averaged LGF for each test. Test reliability of the averaged continuous LGFs were assessed using intraclass correlation coefficients (ICC). Most ICC values showed excellent reliability (>0.9). The LGFs from continuous tests were similar to the overall shapes from discrete tests but were larger by an average of 0.4 dB.