Efferent unmasking of speech-in-noise encoding?

S. B. Smith, B. Cone

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: The medial olivocochlear (MOC) reflex provides efferent feedback from the brainstem to cochlear outer hair cells. Physiologic studies have demonstrated that the MOC reflex is involved in “unmasking” of signals-in-noise at the level of the auditory nerve; however, its functional importance in human hearing remains unclear. Design: This study examined relationships between pre-neural measurements of MOC reflex strength (click-evoked otoacoustic emission inhibition; CEOAE) and neural measurements of speech-in-noise encoding (speech frequency following response; sFFR) in four conditions (Quiet, Contralateral Noise, Ipsilateral Noise, and Ipsilateral + Contralateral Noise). Three measures of CEOAE inhibition (amplitude reduction, effective attenuation, and input-output slope inhibition) were used to quantify pre-neural MOC reflex strength. Correlations between pre-neural MOC reflex strength and sFFR “unmasking” (i.e. response recovery from masking effects with activation of the MOC reflex in time and frequency domains) were assessed. Study sample: 18 young adults with normal hearing. Results: sFFR unmasking effects were insignificant, and there were no correlations between pre-neural MOC reflex strength and sFFR unmasking in the time or frequency domain. Conclusion: Our results do not support the hypothesis that the MOC reflex is involved in speech-in-noise neural encoding, at least for features that are represented in the sFFR at the SNR tested.

Original languageEnglish (US)
JournalInternational Journal of Audiology
DOIs
StateAccepted/In press - 2021

Keywords

  • Efferent
  • frequency following response
  • medial olivocochlear reflex
  • otoacoustic emissions

ASJC Scopus subject areas

  • Language and Linguistics
  • Linguistics and Language
  • Speech and Hearing

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