Exploring the Role of Medial Olivocochlear Efferents on the Detection of Amplitude Modulation for Tones Presented in Noise

Wojtczak, Magdalena; Klang, Alix; Torunsky, Nathan

doi:10.1007/s10162-019-00722-6

Cited by 15 publications

(11 citation statements)

References 84 publications

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“…Finally, our model does not include neural adaptation to stimulus statistics as a potential contributing factor to speech-in-noise discrimination [ 86 , 87 ]. We therefore cannot discount its involvement in the lexical decision task nor show that it is sufficient for robust recognition of degraded speech without the MOC reflex as has been previously suggested [ 86 , 87 , 148 ].…”

Section: Discussionmentioning

confidence: 77%

Understanding degraded speech leads to perceptual gating of a brainstem reflex in human listeners

et al. 2021

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The ability to navigate “cocktail party” situations by focusing on sounds of interest over irrelevant, background sounds is often considered in terms of cortical mechanisms. However, subcortical circuits such as the pathway underlying the medial olivocochlear (MOC) reflex modulate the activity of the inner ear itself, supporting the extraction of salient features from auditory scene prior to any cortical processing. To understand the contribution of auditory subcortical nuclei and the cochlea in complex listening tasks, we made physiological recordings along the auditory pathway while listeners engaged in detecting non(sense) words in lists of words. Both naturally spoken and intrinsically noisy, vocoded speech—filtering that mimics processing by a cochlear implant (CI)—significantly activated the MOC reflex, but this was not the case for speech in background noise, which more engaged midbrain and cortical resources. A model of the initial stages of auditory processing reproduced specific effects of each form of speech degradation, providing a rationale for goal-directed gating of the MOC reflex based on enhancing the representation of the energy envelope of the acoustic waveform. Our data reveal the coexistence of 2 strategies in the auditory system that may facilitate speech understanding in situations where the signal is either intrinsically degraded or masked by extrinsic acoustic energy. Whereas intrinsically degraded streams recruit the MOC reflex to improve representation of speech cues peripherally, extrinsically masked streams rely more on higher auditory centres to denoise signals.

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Section: Discussionmentioning

confidence: 77%

Understanding degraded speech leads to perceptual gating of a brainstem reflex in human listeners

et al. 2021

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“…This conclusion is supported by two other studies. Wojtczak et al (2019) showed that AM sensitivity in noise can improve with a precursor even when the precursor does not change basilar membrane responses (i.e., when it does not activate the MOCR). Second, cochlear-implant users show adaptation to noise in word recognition despite lacking MOCR effects (Marrufo-Pérez et al, 2018), which suggests that mechanisms different from the MOCR can facilitate speech-innoise recognition, at least when the MOCR is absent.…”

Section: Discussionmentioning

confidence: 99%

Adaptation to Noise in Human Speech Recognition Depends on Noise-Level Statistics and Fast Dynamic-Range Compression

et al. 2020

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Human hearing adapts to background noise, as evidenced by the fact that listeners recognize more isolated words when words are presented later rather than earlier in noise. This adaptation likely occurs because the leading noise shifts ("adapts") the dynamic range of auditory neurons, which can improve the neural encoding of speech spectral and temporal cues. Because neural dynamic range adaptation depends on stimulus-level statistics, here we investigated the importance of "statistical" adaptation for improving speech recognition in noisy backgrounds. We compared the recognition of noised-masked words in the presence and in the absence of adapting noise precursors whose level was either constant or was changing every 50 ms according to different statistical distributions. Adaptation was measured for 28 listeners (9 men) and was quantified as the recognition improvement in the precursor relative to the no-precursor condition. Adaptation was largest for constantlevel precursors and did not occur for highly fluctuating precursors, even when the two types of precursors had the same mean level and both activated the medial olivocochlear reflex. Instantaneous amplitude compression of the highly fluctuating precursor produced as much adaptation as the constant-level precursor did without compression. Together, results suggest that noise adaptation in speech recognition is probably mediated by neural dynamic range adaptation to the most frequent sound level. Further, they suggest that auditory peripheral compression per se, rather than the medial olivocochlear reflex, could facilitate noise adaptation by reducing the level fluctuations in the noise.

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“…This variability has generally been attributed to methodological differences in OAE measurement (see [78] for review). Still, more recent studies have questioned whether suppression of cochlear gain by the MOC reflex actually benefits hearing in noise: proposing either a contribution of the reflex to perception only at specific SNRs [24, 78] or, in extremis , that the MOC reflex plays no role, and that neural adaptation to noise statistics may instead underlay robust recognition of degraded speech [73,79,80].…”

Section: Discussionmentioning

confidence: 99%

Perceptual gating of a brainstem reflex facilitates speech understanding in human listeners

Hernández-Pérez

Mikiel-Hunter

McAlpine

et al. 2020

Preprint

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14Navigating "cocktail party" situations by enhancing foreground sounds over irrelevant background 15 information is typically considered from a cortico-centric perspective. However, subcortical circuits, 16 such as the medial olivocochlear reflex (MOCR) that modulates inner ear activity itself, have ample 17 opportunity to extract salient features from the auditory scene prior to any cortical processing. To 18 understand the contribution of auditory subcortical nuclei and the cochleae, physiological 19 recordings were made along the auditory pathway while listeners differentiated non(sense)-words 20 and words. Both naturally-spoken and intrinsically-noisy, vocoded speechfiltering that mimics 21 processing by a cochlear implant-significantly activated the MOCR, whereas listening to speech-22 in-background noise revealed instead engagement of midbrain and cortical resources. An auditory 23 periphery model reproduced these speech degradation-specific effects, providing a rationale for 24 goal-directed MOCR gating to enhance representation of speech features in the auditory nerve. 25These results highlight two strategies co-existing in the auditory system to accommodate 26 categorically different speech degradations. 27 78 cortical auditory responses in both the active listening task and when listeners were required to 79 ignore the task and watch a silent, non-subtitled film. 80Maintaining a fixed task difficulty across speech manipulations, we found measures of hearing 81 function at the level of the cochlea, brainstem, midbrain and cortex to be modulated differently 82 depending on the degradation type applied to speech sounds, and on whether or not speech was 83 3 actively attended. Specifically, the MOCR, assessed in terms of the magnitude of click-evoked 84 OAEs (CEOAEs), was activated by vocoded speech-an intrinsically degraded speech signal-but 85 not by otherwise 'clean' speech presented in either babble-noise or speech-shaped noise. Neural 86 activity at the first synaptic stage of central processing in the cochlear nucleus (CN)-assessed 87 physiologically through auditory brainstem responses (ABRs)-confirmed the reduction in cochlear 88 gain for actively attended vocoded speech, but not speech-in-noise. Conversely, neural activity 89 generated by the auditory midbrain was significantly increased in active vs. passive listening for 90 speech in babble and speech-shaped noise, but not for vocoded speech. This increase was 91 associated with elevated cortical markers of listening effort for the speech-in-noise conditions. A 92 model of the auditory periphery including an MOC circuit with biophysically-realistic temporal 93 dynamics confirmed the stimulus-dependent role of the MOCR in enhancing neural coding of 94 speech signals. Our data suggest that otherwise identical performance in active listening tasks may 95 invoke quite different efferent circuits, requiring different levels of listening effort, depending on the 96 type of stimulus degradation experienced. 98 Results 99Iso-performance in three manipul...

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Exploring the Role of Medial Olivocochlear Efferents on the Detection of Amplitude Modulation for Tones Presented in Noise

Cited by 15 publications

References 84 publications

Understanding degraded speech leads to perceptual gating of a brainstem reflex in human listeners

Understanding degraded speech leads to perceptual gating of a brainstem reflex in human listeners

Adaptation to Noise in Human Speech Recognition Depends on Noise-Level Statistics and Fast Dynamic-Range Compression

Perceptual gating of a brainstem reflex facilitates speech understanding in human listeners

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