Efferent-induced alterations in distortion and reflection otoacoustic emissions in children

Abstract

The medial olivocochlear efferent fibers control outer hair cell responses and inhibit the cochlear-amplifier gain. Measuring efferent function is both theoretically and clinically relevant. In humans, medial efferent inhibition can be assayed via otoacoustic emissions (OAEs). OAEs arise by two fundamentally different mechanisms-nonlinear distortion and coherent reflection. Distortion and reflection emissions are typically applied in isolation for studying the efferent inhibition. Such an approach inadvertently assumes that efferent-induced shifts in distortion and reflection emissions provide redundant information. In this study, efferent-induced shifts in distortion and reflection emissions (click-evoked and stimulus frequency OAEs) were measured in the same subjects-5- to 10-yr-old children. Consistent with the OAE generation theory, efferent-induced shifts in distortion and reflection emissions did not correlate, whereas the two reflection emission shifts correlated. This suggests that using either OAE types provides fragmented information on efferent inhibition and highlights the need to use both distortion and reflection emissions for describing efferent effects.

Auditory deprivation during development alters efferent neural feedback and perception

“…The target frequency range for recording SFOAEs was 707 to 1414 Hz to estimate efferent inhibition at 1000 Hz center frequency. This center frequency has a high SNR for SFOAEs 46,49 , shows robust efferent effects 50 and is free from short-latency components for the probe level 51 . SFOAEs were measured via a suppressor paradigm using 40 dB probe and 60 dB suppressor tones.…”

“…The equipment set-up and calibration for recording swept-tone SFOAEs are previously described by Mishra and Talmadge 46 , The protocol for contralateral stimulation was similar to a previous study 47 . Stimulus generation and recording of signals from the ear canal were performed using the ER-10B+ microphone probe assembly (Etymotic Research, Elk Grove Village, IL).…”

“…Estimates of magnitude, phase, and noise floor were obtained using a least-squared filter modeling 46 . SFOAEs were estimated by minimizing the sum of the squared error between the model and the response.…”

Sexual Dimorphism in the Functional Development of the Cochlear Amplifier in Humans

“…Efferent inhibition was assayed using either CEOAEs or SFOAEs, similar to a previous report (Mishra et al 2018). Of 154 children and 43 adults in whom efferent inhibition data were available, CEOAEs were used to estimate efferent effects in 34 children and 26 adults, while SFOAE-based efferent inhibition was measured in the remaining participants.…”

“…Of 154 children and 43 adults in whom efferent inhibition data were available, CEOAEs were used to estimate efferent effects in 34 children and 26 adults, while SFOAE-based efferent inhibition was measured in the remaining participants. CEOAEs and SFOAEs, being generated via similar mechanisms (Shera & Guinan 1999; Kalluri & Shera 2007), yield efferent effects highly related in magnitude and phase in adults and children (Francis & Guinan 2010; Marshall et al 2014; Mishra et al 2018). Efferent inhibition, in percent change, reported here is the magnitude of the vector difference of the OAE complex pressures and is normalized to individual baseline (Mishra & Biswal 2019).…”