1
|
Goodman SS, Haysley S, Jennings SG. Human Olivocochlear Effects: A Statistical Detection Approach Applied to the Cochlear Microphonic Evoked by Swept Tones. J Assoc Res Otolaryngol 2024:10.1007/s10162-024-00956-z. [PMID: 38954166 DOI: 10.1007/s10162-024-00956-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 06/12/2024] [Indexed: 07/04/2024] Open
Abstract
The human medial olivocochlear (MOC) reflex was assessed by observing the effects of contralateral acoustic stimulation (CAS) on the cochlear microphonic (CM) across a range of probe frequencies. A frequency-swept probe tone (125-4757 Hz, 90 dB SPL) was presented in two directions (up sweep and down sweep) to normal-hearing young adults. This study assessed MOC effects on the CM in individual participants using a statistical approach that calculated minimum detectable changes in magnitude and phase based on CM signal-to-noise ratio (SNR). Significant increases in CM magnitude, typically 1-2 dB in size, were observed for most participants from 354 to 1414 Hz, where the size and consistency of these effects depended on participant, probe frequency, sweep direction, and SNR. CAS-related phase lags were also observed, consistent with CM-based MOC studies in laboratory animals. Observed effects on CM magnitude and phase were in the opposite directions of reported effects on otoacoustic emissions (OAEs). OAEs are sensitive to changes in the motility of outer hair cells located near the peak region of the traveling wave, while the effects of CAS on the CM likely originate from MOC-related changes in the conductance of outer hair cells located in the basal tail of the traveling wave. Thus, MOC effects on the CM are complementary to those observed for OAEs.
Collapse
Affiliation(s)
- Shawn S Goodman
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, USA
| | - Sarah Haysley
- Department of Communication Sciences and Disorders, University of Utah, Salt Lake City, UT, USA
| | - Skyler G Jennings
- Department of Communication Sciences and Disorders, University of Utah, Salt Lake City, UT, USA.
| |
Collapse
|
2
|
Goodman SS, Lefler SM, Lee C, Guinan JJ, Lichtenhan JT. The Origin Along the Cochlea of Otoacoustic Emissions Evoked by Mid-Frequency Tone Pips. J Assoc Res Otolaryngol 2024:10.1007/s10162-024-00955-0. [PMID: 38937327 DOI: 10.1007/s10162-024-00955-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 06/12/2024] [Indexed: 06/29/2024] Open
Abstract
PURPOSE Tone-pip-evoked otoacoustic emissions (PEOAEs) are transient-evoked otoacoustic emissions (OAEs) that are hypothesized to originate from reflection of energy near the best-frequency (BF) cochlear place of the stimulus frequency. However, individual PEOAEs have energy with a wide range of delays. We sought to determine whether some PEOAE energy is consistent with having been generated far from BF. METHODS PEOAEs from 35 and 47 dB SPL tone pips were obtained by removing pip-stimulus energy by subtracting the ear-canal sound pressure from scaled-down 59 dB SPL tone pips (which evoke relatively small OAEs). PEOAE delays were measured at each peak in the PEOAE absolute-value waveforms. While measuring PEOAEs and auditory-nerve compound action potentials (CAPs), amplification was blocked sequentially from apex to base by cochlear salicylate perfusion. The perfusion time when a CAP was reduced identified when the perfusion reached the tone-pip BF place. The perfusion times when each PEOAE peak was reduced identified where along the cochlea it received cochlear amplification. PEOAEs and CAPs were measured simultaneously using one pip frequency in each ear (1.4 to 4 kHz across 16 ears). RESULTS Most PEOAE peaks received amplification primarily between the BF place and 1-2 octaves basal of the BF place. PEOAE peaks with short delays received amplification basal of BF place. PEOAE peaks with longer delays sometimes received amplification apical of BF place, consistent with previous stimulus-frequency-OAE results. CONCLUSION PEOAEs provide information about cochlear amplification primarily within ~ 1.5 octave of the tone-pip BF place, not about regions > 3 octaves basal of BF.
Collapse
Affiliation(s)
- Shawn S Goodman
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa, USA
| | - Shannon M Lefler
- Department of Otolaryngology, Washington University School of Medicine in St. Louis, Saint Louis, MO, USA
| | - Choongheon Lee
- Department of Otolaryngology, University of Rochester, Rochester, NY, USA
| | - John J Guinan
- Massachusetts Eye and Ear, Eaton-Peabody Laboratories, Boston, MA, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, USA
| | - Jeffery T Lichtenhan
- Department of Otolaryngology, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
| |
Collapse
|
3
|
Faubion SL, Park RK, Lichtenhan JT, Jennings SG. Effects of contralateral noise on envelope-following responses, auditory-nerve compound action potentials, and otoacoustic emissions measured simultaneously. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 155:1813-1824. [PMID: 38445988 PMCID: PMC10919957 DOI: 10.1121/10.0025137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 02/15/2024] [Accepted: 02/16/2024] [Indexed: 03/07/2024]
Abstract
This study assessed whether the effects of contralateral acoustic stimulation (CAS) are consistent with eliciting the medial olivocochlear (MOC) reflex for measurements sensitive to outer hair cell (otoacoustic emissions, OAEs), auditory-nerve (AN; compound action potential, CAP), and brainstem/cortical (envelope-following response, EFR) function. The effects of CAS were evaluated for simultaneous measurement of OAEs, CAPs, and EFRs in participants with normal hearing. Clicks were presented at 40 or 98 Hz in three ipsilateral noise conditions (no noise, 45 dB SPL, and 55 dB SPL). For the no noise condition, CAS suppressed or enhanced EFR amplitudes for 40- and 98-Hz clicks, respectively, while CAS had no significant effect on CAP amplitudes. A follow-up experiment using slower rates (4.4-22.2 Hz) assessed whether this insignificant CAS effect on CAPs was from ipsilateral MOC stimulation or AN adaptation; however, CAS effects remained insignificant despite favorable signal-to-noise ratios. CAS-related enhancements of EFR and CAP amplitudes in ipsilateral noise were not observed, contrary to the anti-masking effect of the MOC reflex. EFR and OAE suppression from CAS were not significantly correlated. Thus, the effects of CAS on EFRs may not be solely mediated by the MOC reflex and may be partially mediated by higher auditory centers.
Collapse
Affiliation(s)
- Shelby L Faubion
- Department of Communication Sciences and Disorders, The University of Utah, 390 South, 1530 East, BEHS 1201, Salt Lake City, Utah 84112, USA
| | - Ryan K Park
- Department of Communication Sciences and Disorders, The University of Utah, 390 South, 1530 East, BEHS 1201, Salt Lake City, Utah 84112, USA
| | - Jeffery T Lichtenhan
- Department of Otolaryngology, University of South Florida Morsani College of Medicine, Tampa, Florida 33612, USA
| | - Skyler G Jennings
- Department of Communication Sciences and Disorders, The University of Utah, 390 South, 1530 East, BEHS 1201, Salt Lake City, Utah 84112, USA
| |
Collapse
|
4
|
Carney LH. Neural Fluctuation Contrast as a Code for Complex Sounds: The Role and Control of Peripheral Nonlinearities. Hear Res 2024; 443:108966. [PMID: 38310710 PMCID: PMC10923127 DOI: 10.1016/j.heares.2024.108966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/14/2024] [Accepted: 01/26/2024] [Indexed: 02/06/2024]
Abstract
The nonlinearities of the inner ear are often considered to be obstacles that the central nervous system has to overcome to decode neural responses to sounds. This review describes how peripheral nonlinearities, such as saturation of the inner-hair-cell response and of the IHC-auditory-nerve synapse, are instead beneficial to the neural encoding of complex sounds such as speech. These nonlinearities set up contrast in the depth of neural-fluctuations in auditory-nerve responses along the tonotopic axis, referred to here as neural fluctuation contrast (NFC). Physiological support for the NFC coding hypothesis is reviewed, and predictions of several psychophysical phenomena, including masked detection and speech intelligibility, are presented. Lastly, a framework based on the NFC code for understanding how the medial olivocochlear (MOC) efferent system contributes to the coding of complex sounds is presented. By modulating cochlear gain control in response to both sound energy and fluctuations in neural responses, the MOC system is hypothesized to function not as a simple feedback gain-control device, but rather as a mechanism for enhancing NFC along the tonotopic axis, enabling robust encoding of complex sounds across a wide range of sound levels and in the presence of background noise. Effects of sensorineural hearing loss on the NFC code and on the MOC feedback system are presented and discussed.
Collapse
Affiliation(s)
- Laurel H Carney
- Depts. of Biomedical Engineering, Neuroscience, and Electrical & Computer Engineering University of Rochester, Rochester, NY, USA.
| |
Collapse
|
5
|
Lee D, Lewis JD. Inter-Subject Variability in the Dependence of Medial-Olivocochlear Reflex Strength on Noise Bandwidth. Ear Hear 2023; 44:544-557. [PMID: 36477401 DOI: 10.1097/aud.0000000000001302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
OBJECTIVES The objective of the study was to quantify inter-subject variability in the dependence of the medial-olivocochlear reflex (MOCR) on noise bandwidth. Of specific interest was whether inter-subject variability in MOCR dependence on bandwidth explained variability in the MOCR response elicited by wideband noise. DESIGN Thirty-two young adults with normal hearing participated in the study. Click-evoked otoacoustic emissions were measured in the ipsilateral ear with and without noise presented in the contralateral ear. Presentation of contralateral noise served to activate the MOCR. The MOCR was activated using five different noise stimuli with bandwidths ranging from 1- to 5-octaves wide (center frequency of 2 kHz; bandwidth incremented in 1-octave steps). Noise spectral levels (19.6 dB SPL/Hz) were held constant across all bandwidths. MOCR metrics included the normalized-percent change in the otoacoustic emission (OAE), the MOCR-induced OAE magnitude shift, and the MOCR-induced OAE phase shift. Linear mixed-effect models were fit to model the dependence of MOCR-induced OAE magnitude and phase changes on noise bandwidth. The use of a mixed-effect modeling approach allowed for the estimation of subject-specific model parameters that capture on- and off-frequency contributions to the MOCR effects. Regression analysis was performed to evaluate the predictive capacity of subject-specific model parameters on the MOCR response elicited by wideband noise. RESULTS All OAE-based MOCR metrics increased as the noise bandwidth increased from 1- to 5-octaves wide. The dependence of MOCR-induced OAE magnitude and phase shifts on activator bandwidth was well approximated using a linear model with intercept and slope terms. On average, MOCR-induced magnitude and phase shifts increased at a rate of 0.3 dB/octave and 0.01 cycles/octave, respectively, as bandwidth extended beyond the predicted region of OAE generation. A statistically significant random effect of subject was found for both the intercept and slope parameter of each model. Subject-specific slope estimates were statistically significant predictors of a repeated measure of the wideband MOCR response. A higher slope was predictive of larger wideband MOCR effects. CONCLUSIONS MOCR-induced changes to the OAE are greatest when the MOCR is elicited using wideband noise. Variability in the process of spectral integration within the MOCR pathway appears to explain, in part, inter-subject variability in OAE-based estimates of the MOCR response elicited by wideband noise.
Collapse
Affiliation(s)
- Donguk Lee
- Department of Audiology and Speech Pathology, University of Tennessee Health Science Center, Knoxville, Tennessee, USA
| | | |
Collapse
|
6
|
Lewis JD, Goettl-Meyer M, Lee D. Medial Olivocochlear Reflex Strength in Ears With Low-to-Moderate Annual Noise Exposure. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2023; 66:1428-1443. [PMID: 36940474 DOI: 10.1044/2022_jslhr-22-00433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
PURPOSE Studies in lower mammals demonstrate enhancement of the medial olivocochlear reflex (MOCR) following noise exposure. A similar effect may occur in humans, and there is some evidence of an individual's acoustic history affecting the MOCR. The current work evaluates the relationship between an individual's annual noise exposure history and their MOCR strength. Given the potential role of the MOCR as a biological hearing protector, it is important to identify factors associated with MOCR strength. METHOD Data were collected from 98 normal-hearing young adults. Annual noise exposure history was estimated using the Noise Exposure Questionnaire. MOCR strength was assayed using click-evoked otoacoustic emissions (CEOAEs) measured with and without noise presented to the contralateral ear. MOCR metrics included the MOCR-induced otoacoustic emission (OAE) magnitude shift and phase shift. A CEOAE signal-to-noise ratio (SNR) of at least 12 dB was required for estimation of the MOCR metrics. Linear regression was applied to evaluate the relationship between MOCR metrics and annual noise exposure. RESULTS Annual noise exposure was not a statistically significant predictor of the MOCR-induced CEOAE magnitude shift. However, annual noise exposure was a statistically significant predictor of the MOCR-induced CEOAE phase shift-the MOCR-induced phase shift decreased with increasing noise exposure. Additionally, annual noise exposure was a statistically significant predictor of OAE level. CONCLUSIONS Findings contrast with recent work that suggests MOCR strength increases with annual noise exposure. Compared with previous work, data for this study were collected using more stringent SNR criteria, which is expected to increase the precision of the MOCR metrics. Additionally, data were collected for a larger subject population with a wider range of noise exposures. Whether findings generalize to other exposure durations and levels is unknown and requires future study.
Collapse
Affiliation(s)
- James D Lewis
- Department of Audiology and Speech Pathology, The University of Tennessee Health Science Center, Knoxville
| | - Morgaine Goettl-Meyer
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora
| | - Donguk Lee
- Department of Audiology and Speech Pathology, The University of Tennessee Health Science Center, Knoxville
| |
Collapse
|
7
|
Sensitivity of Vowel-Evoked Envelope Following Responses to Spectra and Level of Preceding Phoneme Context. Ear Hear 2022; 43:1327-1335. [DOI: 10.1097/aud.0000000000001190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
8
|
Boothalingam S, Goodman SS, MacCrae H, Dhar S. A Time-Course-Based Estimation of the Human Medial Olivocochlear Reflex Function Using Clicks. Front Neurosci 2021; 15:746821. [PMID: 34776849 PMCID: PMC8581223 DOI: 10.3389/fnins.2021.746821] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 09/28/2021] [Indexed: 11/22/2022] Open
Abstract
The auditory efferent system, especially the medial olivocochlear reflex (MOCR), is implicated in both typical auditory processing and in auditory disorders in animal models. Despite the significant strides in both basic and translational research on the MOCR, its clinical applicability remains under-utilized in humans due to the lack of a recommended clinical method. Conventional tests employ broadband noise in one ear while monitoring change in otoacoustic emissions (OAEs) in the other ear to index efferent activity. These methods, (1) can only assay the contralateral MOCR pathway and (2) are unable to extract the kinetics of the reflexes. We have developed a method that re-purposes the same OAE-evoking click-train to also concurrently elicit bilateral MOCR activity. Data from click-train presentations at 80 dB peSPL at 62.5 Hz in 13 young normal-hearing adults demonstrate the feasibility of our method. Mean MOCR magnitude (1.7 dB) and activation time-constant (0.2 s) are consistent with prior MOCR reports. The data also suggest several advantages of this method including, (1) the ability to monitor MEMR, (2) obtain both magnitude and kinetics (time constants) of the MOCR, (3) visual and statistical confirmation of MOCR activation.
Collapse
Affiliation(s)
- Sriram Boothalingam
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI, United States.,Waisman Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Shawn S Goodman
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, United States
| | - Hilary MacCrae
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, United States
| | - Sumitrajit Dhar
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, United States.,Knowles Center, Northwestern University, Evanston, IL, United States
| |
Collapse
|