Exploring Middle-Ear-Muscle-Reflex with natural sounds with a focus on hyperacusis
The Middle Ear Muscle Reflex (MEMR) is the mechanism through which the stapedius muscle stiffens the tympanic membrane protecting the inner ear from sound trauma. In clinical practice, the sounds used to test the MEMR are artificial (pure tones, wide-band noise). However, natural sounds also elicit a MEMR. Hyperacusis refer to an abnormal sensitivity to sounds, often diagnosed in connection with a hearing impairment.In this study, we tested the efficacy of natural sounds with varying spectral and emotional content (e.g. pleasantness, fear). It is hypothesized that some natural sounds elicit a MEMR response at lower levels than artificial sounds. It is also hypothesized that the loudness/annoyance perceived for natural sounds could be lower than for artificial sounds for equally strong MEMR. The individual MEMR thresholds were compared with the results of two questionnaires, hyperacusis (HQ) and noise sensitivity.The results showed that some sounds are more efficient than others at the same stimulus intensity. Moreover, natural sounds were mainly rated as less loud/annoying than the artificial ones. However, the variability across subjects revealed the need for a more subject-specific analysis considering the presence or not of an hyperacusis trend.