PT  - JOURNAL ARTICLE
AU  - Heivet Hernandez-Perez
AU  - Jason Mikiel-Hunter
AU  - David McAlpine
AU  - Sumitrajit Dhar
AU  - Sriram Boothalingam
AU  - Jessica J.M. Monaghan
AU  - Catherine M. McMahon
TI  - Perceptual gating of a brainstem reflex facilitates speech understanding in human listeners
AID  - 10.1101/2020.05.31.115444
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2020.05.31.115444
4099  - http://biorxiv.org/content/early/2021/03/19/2020.05.31.115444.1.short
4100  - http://biorxiv.org/content/early/2021/03/19/2020.05.31.115444.1.full
AB  - Navigating “cocktail party” situations by enhancing foreground sounds over irrelevant background information is typically considered from a cortico-centric perspective. However, subcortical circuits, such as the medial olivocochlear (MOC) reflex that modulates inner ear activity itself, have ample opportunity to extract salient features from the auditory scene prior to any cortical processing. To understand the contribution of auditory subcortical nuclei and the cochlea, physiological recordings were made along the auditory pathway while listeners differentiated non(sense)-words and words. Both naturally-spoken and intrinsically-noisy, vocoded speech — filtering that mimics processing by a cochlear implant—significantly activated the MOC reflex, whereas listening to speech-in-background noise revealed instead engagement of midbrain and cortical resources. An auditory periphery model reproduced these speech degradation-specific effects, providing a rationale for goal-directed gating of the MOC reflex to enhance representation of speech features in the auditory nerve. Our data reveals the co-existence of two strategies in the auditory system that may facilitate speech understanding in situations where the speech signal is either intrinsically degraded or masked by extrinsic auditory information.Competing Interest StatementThe authors have declared no competing interest.