scholarly journals Behavioral Measures of Cochlear Gain Reduction Depend on Precursor Frequency, Bandwidth, and Level

2021 ◽  
Vol 15 ◽  
Author(s):  
Kristina DeRoy Milvae ◽  
Elizabeth A. Strickland
Keyword(s):  
Physiological Mechanism ◽  
Otoacoustic Emission ◽  
Broadband Noise ◽  
Signal Frequency ◽  
Frequency Content ◽  
Afferent Fibers ◽  
Gain Reduction ◽  
Cochlear Gain ◽  
Medial Olivocochlear ◽  
Signal Threshold

Sensory systems adjust to the environment to maintain sensitivity to change. In the auditory system, the medial olivocochlear reflex (MOCR) is a known physiological mechanism capable of such adjustment. The MOCR provides efferent feedback between the brainstem and cochlea, reducing cochlear gain in response to sound. The perceptual effects of the MOCR are not well understood, such as how gain reduction depends on elicitor characteristics in human listeners. Physiological and behavioral data suggest that ipsilateral MOCR tuning is only slightly broader than it is for afferent fibers, and that the fibers feed back to the frequency region of the cochlea that stimulated them. However, some otoacoustic emission (OAE) data suggest that noise is a more effective elicitor than would be consistent with sharp tuning, and that a broad region of the cochlea may be involved in elicitation. If the elicitor is processed in a cochlear channel centered at the signal frequency, the growth of gain reduction with elicitor level would be expected to depend on the frequency content of the elicitor. In the current study, the effects of the frequency content and level of a preceding sound (called a precursor) on signal threshold was examined. The results show that signal threshold increased with increasing precursor level at a shallower slope for a tonal precursor at the signal frequency than for a tonal precursor nearly an octave below the signal frequency. A broadband noise was only slightly more effective than a tone at the signal frequency, with a relatively shallow slope similar to that of the tonal precursor at the signal frequency. Overall, these results suggest that the excitation at the signal cochlear place, regardless of elicitor frequency, determines the magnitude of ipsilateral cochlear gain reduction, and that it increases with elicitor level.

scholarly journals Correlation and Reliability of Behavioral and Otoacoustic-Emission Estimates of Contralateral Medial Olivocochlear Reflex Strength in Humans

2021 ◽  
Vol 15 ◽  
Author(s):  
Miriam I. Marrufo-Pérez ◽  
Peter T. Johannesen ◽  
Enrique A. Lopez-Poveda
Keyword(s):  
Otoacoustic Emission ◽  
Acoustic Stimulation ◽  
Broadband Noise ◽  
Distortion Product Otoacoustic Emission ◽  
Detection Thresholds ◽  
Medial Olivocochlear Reflex ◽  
Distortion Product ◽  
Healthy Humans ◽  
Medial Olivocochlear ◽  
Tone Detection

The roles of the medial olivocochlear reflex (MOCR) in human hearing have been widely investigated but remain controversial. We reason that this may be because the effects of MOCR activation on cochlear mechanical responses can be assessed only indirectly in healthy humans, and the different methods used to assess those effects possibly yield different and/or unreliable estimates. One aim of this study was to investigate the correlation between three methods often employed to assess the strength of MOCR activation by contralateral acoustic stimulation (CAS). We measured tone detection thresholds (N = 28), click-evoked otoacoustic emission (CEOAE) input/output (I/O) curves (N = 18), and distortion-product otoacoustic emission (DPOAE) I/O curves (N = 18) for various test frequencies in the presence and the absence of CAS (broadband noise of 60 dB SPL). As expected, CAS worsened tone detection thresholds, suppressed CEOAEs and DPOAEs, and horizontally shifted CEOAE and DPOAE I/O curves to higher levels. However, the CAS effect on tone detection thresholds was not correlated with the horizontal shift of CEOAE or DPOAE I/O curves, and the CAS-induced CEOAE suppression was not correlated with DPOAE suppression. Only the horizontal shifts of CEOAE and DPOAE I/O functions were correlated with each other at 1.5, 2, and 3 kHz. A second aim was to investigate which of the methods is more reliable. The test–retest variability of the CAS effect was high overall but smallest for tone detection thresholds and CEOAEs, suggesting that their use should be prioritized over the use of DPOAEs. Many factors not related with the MOCR, including the limited parametric space studied, the low resolution of the I/O curves, and the reduced numbers of observations due to data exclusion likely contributed to the weak correlations and the large test–retest variability noted. These findings can help us understand the inconsistencies among past studies and improve our understanding of the functional significance of the MOCR.

scholarly journals Fast, Slow, and Steady-State Effects of Contralateral Acoustic Activation of the Medial Olivocochlear Efferent System in Awake Guinea Pigs: Action of Gentamicin

1997 ◽  
Vol 78 (4) ◽  
pp. 1826-1836 ◽  
Author(s):  
Deise Lima da Costa ◽  
Anne Chibois ◽  
Jean-Paul Erre ◽  
Christophe Blanchet ◽  
RENAUD CHARLET de Sauvage ◽  
...  
Keyword(s):  
Steady State ◽  
Time Constant ◽  
Decay Time ◽  
Guinea Pigs ◽  
Round Window ◽  
Broadband Noise ◽  
Decay Time Constant ◽  
Efferent System ◽  
Medial Olivocochlear ◽  
Medial Olivocochlear Efferent System

Lima da Costa, Deise, Anne Chibois, Jean-Paul Erre, Christophe Blanchet, Renaud Charlet de Sauvage, and Jean-Marie Aran. Fast, slow, and steady-state effects of contralateral acoustic activation of the medial olivocochlear efferent system in awake guinea pigs: action of gentamicin. J. Neurophysiol. 78: 1826–1836, 1997. The function of the medial olivocochlear efferent system was observed in awake guinea pigs by recording, in the absence of ipsilateral external acoustic stimulation, the ensemble background activity (EBA) of the VIIIth nerve from an electrode chronically implanted on the round window of one ear. The EBA was measured by calculating the power value of the round window signal in the 0.5- to 2.5-kHz band after digital or analog (active) filtering. This EBA was compared with and without the addition of a low-level broadband noise to the opposite ear. The contralateral broadband noise (CLBN, 55 dB SPL) induced, via the efferent system, a decrease (suppression) of this EBA. With the use of noise bursts of different durations, two components in this suppression could be observed. After the onset of a 1-s CLBN, the power value of the EBA decreased rapidly by 38.0 ± 4.2% (mean ± SD, n = 3), with a latency of <10 ms and a decay time constant of 13.1 ± 1.0 ms (fast effect). At the offset of the 1-s CLBN, EBA came back to prestimulation values with a similar latency and a time constant of 15.5 ± 2.9 ms. During longer CLBN stimulation (≥1 min), EBA presented, after the fast decrease, an additional, slower decrease of 15.6 ± 3.1%, with a delay of 9.8 ± 1.3 s and a decay time constant of 16.1 ± 5.0 s ( n = 12, slow effect), and then remained remarkably constant for as long as observed, i.e., >2 h (steady state). The average global suppression was thus up to 47.8 ± 5.8% of the basal, pre-CLBN-stimulation EBA value. At the offset of the CLBN, EBA returned to pre-CLBN level with fast and slow phases, with, for the slow phase, no delay and a time constant of 32.1 ± 8.1 s. Fast and slow changes in EBA power values were observed after a single injection of gentamicin (GM) at different doses (150, 200, and 250 mg/kg). At 150 and 200 mg/kg, GM progressively and reversibly blocked the rapid effect, but the slow component of the efferent medial suppression remained remarkably unchanged. However, at higher doses both the fast and slow suppressions were totally yet still reversibly blocked. These observations indicate that the medial olivocochlear efferent system exerts sustained influences on outer hair cells and that this effect develops in two different steps that may have different basic cellular mechanisms.

scholarly journals Investigating Influences of Medial Olivocochlear Efferent System on Central Auditory Processing and Listening in Noise: A Behavioral and Event-Related Potential Study

2020 ◽  
Vol 10 (7) ◽  
pp. 428
Author(s):  
Aparna Rao ◽  
Tess K. Koerner ◽  
Brandon Madsen ◽  
Yang Zhang
Keyword(s):  
Word Recognition ◽  
Otoacoustic Emission ◽  
Event Related Potential ◽  
Behavioral Performance ◽  
Contralateral Stimulation ◽  
Related Potentials ◽  
Noise Test ◽  
Medial Olivocochlear ◽  
Listening In Noise ◽  
Physiological Tests

This electrophysiological study investigated the role of the medial olivocochlear (MOC) efferents in listening in noise. Both ears of eleven normal-hearing adult participants were tested. The physiological tests consisted of transient-evoked otoacoustic emission (TEOAE) inhibition and the measurement of cortical event-related potentials (ERPs). The mismatch negativity (MMN) and P300 responses were obtained in passive and active listening tasks, respectively. Behavioral responses for the word recognition in noise test were also analyzed. Consistent with previous findings, the TEOAE data showed significant inhibition in the presence of contralateral acoustic stimulation. However, performance in the word recognition in noise test was comparable for the two conditions (i.e., without contralateral stimulation and with contralateral stimulation). Peak latencies and peak amplitudes of MMN and P300 did not show changes with contralateral stimulation. Behavioral performance was also maintained in the P300 task. Together, the results show that the peripheral auditory efferent effects captured via otoacoustic emission (OAE) inhibition might not necessarily be reflected in measures of central cortical processing and behavioral performance. As the MOC effects may not play a role in all listening situations in adults, the functional significance of the cochlear effects of the medial olivocochlear efferents and the optimal conditions conducive to corresponding effects in behavioral and cortical responses remain to be elucidated.

Acoustic Non-Reciprocal Band Structure in a Passive, Nonlinear, 1D Material

2019 ◽  
Author(s):  
Lezheng Fang ◽  
Amir Darabi ◽  
Alexander F. Vakakis ◽  
Michael J. Leamy
Keyword(s):  
Numerical Study ◽  
The Other ◽  
Signal Frequency ◽  
Strong Nonlinearity ◽  
Frequency Content ◽  
Minimal Distortion ◽  
Shape Structure ◽  
Band Pass ◽  
Path Dependent ◽  
Mechanical Devices

Abstract Acoustic non-reciprocity, referring to the phenomenon of path-dependent propagation, has diverse applications in mechanical devices. This paper presents a numerical study on a periodic triangle-shape structure that breaks reciprocity in a passive manner over a broad range of frequency and energy. The proposed structure contains strong nonlinearity and geometric asymmetry, which contributes to a direction-dependent dispersion relationship. When the signal frequency falls in the band pass in one direction, and band gap in the other, a unidirectional wave propagation results. The system achieves giant non-reciprocity with minimal distortion in the frequency content of the signal.

Behavioral explorations of cochlear gain reduction

2014 ◽  
Vol 135 (4) ◽  
pp. 2384-2384
Author(s):  
Elizabeth A. Strickland ◽  
Elin Roverud ◽  
Kristina DeRoy Milvae
Keyword(s):  
Gain Reduction ◽  
Cochlear Gain

scholarly journals Spontaneous otoacoustic emission recordings during contralateral pure-tone activation of medial olivocochlear reflex

2017 ◽  
Vol 104 (2) ◽  
pp. 171-182
Author(s):  
E Bulut ◽  
L Öztürk
Keyword(s):  
Pure Tone ◽  
Outer Hair Cell ◽  
Basilar Membrane ◽  
Otoacoustic Emission ◽  
Frequency Discrimination ◽  
Frequency Range ◽  
Unilateral Deafness ◽  
Transient Evoked Otoacoustic Emission ◽  
Medial Olivocochlear ◽  
Bilateral Deafness

We hypothesized that cochlear frequency discrimination occurs through medial olivocochlear efferent (MOCE)-induced alterations in outer hair cell (OHC) electromotility, which is independent from basilar membrane traveling waves. After obtaining informed consent, volunteers with normal hearing (n = 10; mean age: 20.6 ± 1.2 years) and patients with unilateral deafness (n = 10; mean age: 30.2 ± 17.9 years) or bilateral deafness (n = 8; mean age: 30.7 ± 13.8 years) underwent a complete physical and audiological examination, and audiological tests including transient evoked otoacoustic emission and spontaneous otoacoustic emission (TEOAE and SOAE, respectively). SOAE recordings were performed during contralateral pure-tone stimuli at 1 and 3 kHz. SOAE recordings in the presence of contralateral pure-tone stimuli showed frequency-specific activation out of the initial frequency range of SOAE responses. Basilar membrane motion during pure-tone stimulation results from OHC activation by means of MOCE neurons rather than from a traveling wave. Eventually, frequency-specific responses obtained from SOAEs suggested that OHC electromotility may be responsible for frequency discrimination of the cochlea independently from basilar membrane motion.

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