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Abdala C, Luo P, Shera CA. Characterizing the Relationship Between Reflection and Distortion Otoacoustic Emissions in Normal-Hearing Adults. J Assoc Res Otolaryngol 2022; 23:647-664. [PMID: 35804277 PMCID: PMC9613820 DOI: 10.1007/s10162-022-00857-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 06/24/2022] [Indexed: 11/28/2022] Open
Abstract
Otoacoustic emissions (OAEs) arise from one (or a combination) of two basic generation mechanisms in the cochlea: nonlinear distortion and linear reflection. As a result of having distinct generation processes, these two classes of emissions may provide non-redundant information about hair-cell integrity and show distinct sensitivities to cochlear pathology. Here, we characterize the relationship between reflection and distortion emissions in normal hearers across a broad frequency and stimulus-level space using novel analysis techniques. Furthermore, we illustrate the promise of this approach in a small group of individuals with mild-moderate hearing loss. A "joint-OAE profile" was created by measuring interleaved swept-tone stimulus-frequency OAEs (SFOAEs) and 2f1-f2 distortion-product OAEs (DPOAEs) in the same ears using well-considered parameters. OAE spectra and input/output functions were calculated across five octaves. Using our specific recording protocol and analysis scheme, SFOAEs in normal hearers had higher levels than did DPOAEs, with the most pronounced differences occurring at the highest stimulus levels. Also, SFOAE compression occurred at higher stimulus levels (than did DPOAE compression) and its growth in the compressed region was steeper. The diagnostic implications of these findings and the influence of the measurement protocol on both OAEs (and on their relationship) are discussed.
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Affiliation(s)
- Carolina Abdala
- Auditory Research Center, Caruso Department of Otolaryngology, University of Southern California, Los Angeles, CA, 90033, USA.
| | - Ping Luo
- Auditory Research Center, Caruso Department of Otolaryngology, University of Southern California, Los Angeles, CA, 90033, USA
| | - Christopher A Shera
- Auditory Research Center, Caruso Department of Otolaryngology, University of Southern California, Los Angeles, CA, 90033, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, 90089, USA
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Wang Y, Qi Z, Yu M, Wang J, Chen R. Characteristic of Stimulus Frequency Otoacoustic Emissions: Detection Rate, Musical Training Influence, and Gain Function. Brain Sci 2019; 9:E255. [PMID: 31561573 PMCID: PMC6827094 DOI: 10.3390/brainsci9100255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/18/2019] [Accepted: 09/25/2019] [Indexed: 11/16/2022] Open
Abstract
Stimulus frequency otoacoustic emission (SFOAE) is an active acoustic signal emitted by the inner ear providing salient information about cochlear function and dysfunction. To provide a basis for laboratory investigation and clinical use, we investigated the characteristics of SFOAEs, including detection rate, musical training influence, and gain function. Sixty-five normal hearing subjects (15 musicians and 50 non-musicians, aged 16-45 years) were tested and analyzed at the probe level of 30 and 50 dB sound pressure levels (SPL) in the center frequency of 1 and 4 kHz in the study. The results indicate that (1) the detection rates of SFOAE are sensitive to the gender, (2) musicians reveal enhanced hearing capacity and SFOAE amplitudes compared with non-musicians, and (3) probe frequency has a significant effect on the compression threshold of SFOAE. Our findings highlight the importance of SFOAE in the clinical hearing screening and diagnosis and emphasize the use of musical training for the rehabilitation enhancement of the auditory periphery and hearing threshold.
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Affiliation(s)
- Yao Wang
- Department of Biomedical Engineering, School of Life Sciences, Tianjin Polytechnic University, Tianjin 300387, China.
| | - Zhihang Qi
- Department of Biomedical Engineering, School of Life Sciences, Tianjin Polytechnic University, Tianjin 300387, China.
| | - Mengmeng Yu
- Department of Biomedical Engineering, School of Life Sciences, Tianjin Polytechnic University, Tianjin 300387, China.
| | - Jinhai Wang
- Department of Biomedical Engineering, School of Life Sciences, Tianjin Polytechnic University, Tianjin 300387, China.
| | - Ruijuan Chen
- Department of Biomedical Engineering, School of Life Sciences, Tianjin Polytechnic University, Tianjin 300387, China.
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Abdala C, Kalluri R. Towards a joint reflection-distortion otoacoustic emission profile: Results in normal and impaired ears. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 142:812. [PMID: 28863614 PMCID: PMC5552396 DOI: 10.1121/1.4996859] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/14/2017] [Accepted: 07/17/2017] [Indexed: 05/12/2023]
Abstract
Otoacoustic emissions (OAEs) provide salient information about cochlear function and dysfunction. Two broad classes of emissions, linear reflection and nonlinear distortion, arise via distinct cochlear processes and hence, appear to provide independent information about cochlear health and hearing. Considered in combination, these two OAE types may characterize sensory hearing loss most effectively. In this study, the level-dependent growth of stimulus-frequency OAEs (a reflection-type emission) and distortion-product OAEs (a distortion-type emission) were measured in ten normal-hearing ears and eight ears with slight-to-moderate sensorineural hearing loss. Metrics of OAE strength and compression were derived from OAE input/output functions and then considered in a combined fashion. Results indicate that SFOAEs and DPOAEs differ significantly in their strength and compression features. When SFOAE and DPOAE metrics are displayed together on a two-dimensional plot, relatively well-defined data clusters describe their normative relationship. In hearing-impaired ears, this relationship is disrupted but not in a uniform way across ears; ears with similar audiograms showed differently altered joint-OAE profiles. Hearing loss sometimes affected only one OAE or one more than the other. Results suggest a joint-OAE profile is promising and warrants study in a large group of subjects with sensory hearing loss of varied etiologies.
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Affiliation(s)
- Carolina Abdala
- Caruso Department of Otolaryngology, Auditory Research Center, University of Southern California, 1640 Marengo Street, Suite 326, Los Angeles, California 90033, USA
| | - Radha Kalluri
- Caruso Department of Otolaryngology, Auditory Research Center, University of Southern California, 1640 Marengo Street, Suite 326, Los Angeles, California 90033, USA
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Charaziak KK, Souza PE, Siegel JH. Exploration of stimulus-frequency otoacoustic emission suppression tuning in hearing-impaired listeners. Int J Audiol 2014; 54:96-105. [PMID: 25290042 DOI: 10.3109/14992027.2014.941074] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Otoacoustic emissions (OAEs) can provide useful measures of tuning of auditory filters. We previously established that stimulus-frequency (SF) OAE suppression tuning curves (STCs) reflect major features of behavioral tuning (psychophysical tuning curves, PTCs) in normally-hearing listeners. Here, we aim to evaluate whether SFOAE STCs reflect changes in PTC tuning in cases of abnormal hearing. DESIGN PTCs and SFOAE STCs were obtained at 1 kHz and/or 4 kHz probe frequencies. For exploratory purposes, we collected SFOAEs measured across a wide frequency range and contrasted them to commonly measured distortion product (DP) OAEs. STUDY SAMPLE Thirteen listeners with varying degrees of sensorineural hearing loss. RESULTS Except for a few listeners with the most hearing loss, the listeners had normal/nearly normal PTCs. However, attempts to record SFOAE STCs in hearing-impaired listeners were challenging and sometimes unsuccessful due to the high level of noise at the SFOAE frequency, which is not a factor for DPOAEs. In cases of successful measurements of SFOAE STCs there was a large variability in agreement between SFOAE STC and PTC tuning. CONCLUSIONS These results indicate that SFOAE STCs cannot substitute for PTCs in cases of abnormal hearing, at least with the paradigm adopted in this study.
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Affiliation(s)
- Karolina K Charaziak
- The Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, School of Communication, Northwestern University , Evanston , USA
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Chen S, Deng J, Bian L, Li G. Stimulus frequency otoacoustic emissions evoked by swept tones. Hear Res 2013; 306:104-14. [DOI: 10.1016/j.heares.2013.09.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 09/03/2013] [Accepted: 09/26/2013] [Indexed: 10/26/2022]
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Charaziak KK, Souza P, Siegel JH. Stimulus-frequency otoacoustic emission suppression tuning in humans: comparison to behavioral tuning. J Assoc Res Otolaryngol 2013; 14:843-62. [PMID: 24013802 DOI: 10.1007/s10162-013-0412-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 08/11/2013] [Indexed: 11/30/2022] Open
Abstract
As shown by the work of Kemp and Chum in 1980, stimulus-frequency otoacoustic emission suppression tuning curves (SFOAE STCs) have potential to objectively estimate behaviorally measured tuning curves. To date, this potential has not been tested. This study aims to do so by comparing SFOAE STCs and behavioral measures of tuning (simultaneous masking psychophysical tuning curves, PTCs) in 10 normal-hearing listeners for frequency ranges centered around 1,000 and 4,000 Hz at low probe levels. Additionally, SFOAE STCs were collected for varying conditions (probe level and suppression criterion) to identify the optimal parameters for comparison with behavioral data and to evaluate how these conditions affect the features of SFOAE STCs. SFOAE STCs qualitatively resembled PTCs: they demonstrated band-pass characteristics and asymmetric shapes with steeper high-frequency sides than low, but unlike PTCs they were consistently tuned to frequencies just above the probe frequency. When averaged across subjects the shapes of SFOAE STCs and PTCs showed agreement for most recording conditions, suggesting that PTCs are predominantly shaped by the frequency-selective filtering and suppressive effects of the cochlea. Individual SFOAE STCs often demonstrated irregular shapes (e.g., "double-tips"), particularly for the 1,000-Hz probe, which were not observed for the same subject's PTC. These results show the limited utility of SFOAE STCs to assess tuning in an individual. The irregularly shaped SFOAE STCs may be attributed to contributions from SFOAE sources distributed over a region of the basilar membrane extending beyond the probe characteristic place, as suggested by a repeatable pattern of SFOAE residual phase shifts observed in individual data.
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Affiliation(s)
- Karolina K Charaziak
- Department of Communication Sciences and Disorders, Northwestern University, School of Communication, 2240 Campus Drive, Evanston, IL, 602080-2952, USA,
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Johnson TA, Beshaler L. Influence of stimulus parameters on amplitude-modulated stimulus frequency otoacoustic emissions. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2013; 134:1121-33. [PMID: 23927112 PMCID: PMC3745488 DOI: 10.1121/1.4812766] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 06/07/2013] [Accepted: 06/12/2013] [Indexed: 06/02/2023]
Abstract
The present study evaluated the influence of suppressor frequency (fs) and level (Ls) on stimulus-frequency otoacoustic emissions (SFOAEs) recorded using the amplitude-modulated (AM) suppressor technique described by Neely et al. [J. Acoust. Soc. Am. 118, 2124-2127 (2005a)]. Data were collected in normal-hearing subjects, with data collection occurring in two phases. In phase 1, SFOAEs were recorded with probe frequency (fp) = 1, 2, and 4 kHz and probe levels (Lp) ranging from 0 to 60 dB sound pressure level (SPL). At each fp, Ls ranged from Ls = Lp to Ls = Lp + 30 dB. Additionally, nine relationships between fs and fp were evaluated, ranging from fs/fp = 0.80 to fs/fp = 1.16. Results indicated that for low suppressor levels, suppressors higher in frequency than fp (fs > fp) resulted in higher AM-SFOAE levels than suppressors lower in frequency than fp (fs < fp). At higher suppressor levels, suppressors both higher and lower in frequency than fp produced similar AM-SFOAE levels, and, in many cases, low-frequency suppressors produced the largest response. Recommendations for stimulus parameters that maximize AM-SFOAE level were derived from these data. In phase 2, AM-SFOAEs were recorded using these parameters for fp = 0.7-8 kHz and Lp = 20-60 dB SPL. Robust AM-SFOAE responses were recorded in this group of subjects using the parameters developed in phase 1.
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Affiliation(s)
- Tiffany A Johnson
- University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
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Bentsen T, Harte JM, Dau T. Human cochlear tuning estimates from stimulus-frequency otoacoustic emissions. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 129:3797-807. [PMID: 21682403 DOI: 10.1121/1.3575596] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Two objective measures of human cochlear tuning, using stimulus-frequency otoacoustic emissions (SFOAE), have been proposed. One measure used SFOAE phase-gradient delay and the other two-tone suppression (2TS) tuning curves. Here, it is hypothesized that the two measures lead to different frequency functions in the same listener. Two experiments were conducted in ten young adult normal-hearing listeners in three frequency bands (1-2 kHz, 3-4 kHz and 5-6 kHz). Experiment 1 recorded SFOAE latency as a function of stimulus frequency, and experiment 2 recorded 2TS iso-input tuning curves. In both cases, the output was converted into a sharpness-of-tuning factor based on the equivalent rectangular bandwidth. In both experiments, sharpness-of-tuning curves were shown to be frequency dependent, yielding sharper relative tuning with increasing frequency. Only a weak frequency dependence of the sharpness-of-tuning curves was observed for experiment 2, consistent with objective and behavioural estimates from the literature. Most importantly, the absolute difference between the two tuning estimates was very large and statistically significant. It is argued that the 2TS estimates of cochlear tuning likely represents the underlying properties of the suppression mechanism, and not necessarily cochlear tuning. Thus the phase-gradient delay estimate is the most likely one to reflect cochlear tuning.
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Affiliation(s)
- Thomas Bentsen
- Center for Applied Hearing Research, Department of Electrical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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Walsh KP, Pasanen EG, McFadden D. Overshoot measured physiologically and psychophysically in the same human ears. Hear Res 2010; 268:22-37. [PMID: 20430072 PMCID: PMC2923227 DOI: 10.1016/j.heares.2010.04.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 04/18/2010] [Accepted: 04/21/2010] [Indexed: 11/15/2022]
Abstract
A nonlinear version of the stimulus-frequency otoacoustic emission (SFOAE) was measured using stimulus waveforms similar to those used for behavioral overshoot. Behaviorally, the seven listeners were as much as 11 dB worse at detecting a brief tonal signal (4.0 kHz, 10 ms in duration) when it occurred soon after the onset of a wideband masking noise (0.1-6.0 kHz; 400 ms in duration) than when it was delayed by about 200 ms, and the nonlinear SFOAE measure exhibited a similar effect. When either lowpass (0.1-3.8 kHz) or bandpass noise (3.8-4.2 kHz) was used instead of the wideband noise, the physiological and behavioral measures again were similar. When a highpass noise (4.2-6.0 kHz) was used, the physiological and behavioral measures both showed no overshoot-like effect for five of the subjects. The physiological response to the tone decayed slowly after the termination of the noise, much like the time course of resetting for behavioral overshoot. One subject exhibited no overshoot behaviorally even though his cochlear responses were like those of the other subjects. Overall, the evidence suggests that some basic characteristics of overshoot are obligatory consequences of cochlear function, as modulated by the olivocochlear efferent system.
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Affiliation(s)
- Kyle P Walsh
- Department of Psychology, Center for Perceptual Systems, Seay Building, 1 University Station, A8000, University of Texas, Austin, TX 78712-0187, USA.
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Walsh KP, Pasanen EG, McFadden D. Properties of a nonlinear version of the stimulus-frequency otoacoustic emission. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2010; 127:955-69. [PMID: 20136218 PMCID: PMC2830262 DOI: 10.1121/1.3279832] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 12/04/2009] [Accepted: 12/07/2009] [Indexed: 05/19/2023]
Abstract
A procedure for extracting the nonlinear component of the stimulus-frequency otoacoustic emission (SFOAE) is described. This nSFOAE measures the amount by which the cochlear response deviates from linear additivity when the input stimulus is doubled in amplitude. When a 4.0-kHz tone was presented alone, the magnitude of the nSFOAE response remained essentially constant throughout the 400-ms duration of the tone; response magnitude did increase monotonically with increasing tone level. When a wideband noise was presented alone, nSFOAE magnitude increased over the initial 100- to 200-ms portion of the 400-ms duration of the noise. When the tone and the wideband noise were presented simultaneously, nSFOAE magnitude decreased momentarily, then increased substantially for about the first 100 ms and then remained strong for the remainder of the presentation. Manipulations of the noise bandwidth revealed that the low-frequency components were primarily responsible for this rising, dynamic response; no rising segment was seen with bandpass or highpass noise. The rising, dynamic nSFOAE response is likely attributable to activation of the medial olivocochlear efferent system. This perstimulatory emission appears to have the potential to provide information about the earliest stages of auditory processing for stimuli commonly used in psychoacoustical tasks.
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Affiliation(s)
- Kyle P Walsh
- Department of Psychology and Center for Perceptual Systems, 1 University Station A8000, University of Texas, Austin, Texas 78712-0187, USA.
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Keefe DH, Schairer KS, Ellison JC, Fitzpatrick DF, Jesteadt W. Use of stimulus-frequency otoacoustic emissions to investigate efferent and cochlear contributions to temporal overshoot. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2009; 125:1595-604. [PMID: 19275317 PMCID: PMC2677284 DOI: 10.1121/1.3068443] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 12/09/2008] [Accepted: 12/09/2008] [Indexed: 05/24/2023]
Abstract
Behavioral threshold for a tone burst presented in a long-duration noise masker decreases as the onset of the tone burst is delayed relative to masker onset. The threshold difference between detection of early- and late-onset tone bursts is called overshoot. Although the underlying mechanisms are unclear, one hypothesis is that overshoot occurs due to efferent suppression of cochlear nonlinearity [von Klitzing, R., and Kohlrausch, A. (1994). J. Acoust. Soc. Am. 95, 2192-2201]. This hypothesis was tested by using overshoot conditions to elicit stimulus-frequency otoacoustic emissions (SFOAEs), which provide a physiological measure of cochlear nonlinearity. SFOAE and behavioral thresholds were estimated using a modified maximum-likelihood yes-no procedure. The masker was a 400-ms "frozen" notched noise. The signal was a 20-ms, 4-kHz tone burst presented at 1 or 200 ms after the noise onset. Behavioral overshoot results replicated previous studies, but no overshoot was observed in SFOAE thresholds. This suggests that either efferent suppression of cochlear nonlinearity is not involved in overshoot, or a SFOAE threshold estimation procedure based on stimuli similar to those used to study behavioral overshoot is not sensitive enough to measure the effect.
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Affiliation(s)
- Douglas H Keefe
- Boys Town National Research Hospital, Omaha, Nebraska 68131, USA.
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Keefe DH, Ellison JC, Fitzpatrick DF, Gorga MP. Two-tone suppression of stimulus frequency otoacoustic emissions. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2008; 123:1479-94. [PMID: 18345837 PMCID: PMC2517244 DOI: 10.1121/1.2828209] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Stimulus frequency otoacoustic emissions (SFOAEs) measured using a suppressor tone in human ears are analogous to two-tone suppression responses measured mechanically and neurally in mammalian cochleae. SFOAE suppression was measured in 24 normal-hearing adults at octave frequencies (f(p)=0.5-8.0 kHz) over a 40 dB range of probe levels (L(p)). Suppressor frequencies (f(s)) ranged from -2.0 to 0.7 octaves re: f(p), and suppressor levels ranged from just detectable suppression to full suppression. The lowest suppression thresholds occurred for "best" f(s) slightly higher than f(p). SFOAE growth of suppression (GOS) had slopes close to one at frequencies much lower than best f(s), and shallow slopes near best f(s), which indicated compressive growth close to 0.3 dBdB. Suppression tuning curves constructed from GOS functions were well defined at 1, 2, and 4 kHz, but less so at 0.5 and 8.0 kHz. Tuning was sharper at lower L(p) with an equivalent rectangular bandwidth similar to that reported behaviorally for simultaneous masking. The tip-to-tail difference assessed cochlear gain, increasing with decreasing L(p) and increasing f(p) at the lowest L(p) from 32 to 45 dB for f(p) from 1 to 4 kHz. SFOAE suppression provides a noninvasive measure of the saturating nonlinearities associated with cochlear amplification on the basilar membrane.
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Affiliation(s)
- Douglas H Keefe
- Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA.
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Withnell RH, Hazlewood C, Knowlton A. Reconciling the origin of the transient evoked ototacoustic emission in humans. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2008; 123:212-21. [PMID: 18177152 DOI: 10.1121/1.2804635] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A pervasive theme in the literature for the transient evoked otoacoustic emission (TEOAE) measured from the human ear canal has been one of the emission arising solely (or largely) from a single, place-fixed mechanism. Here TEOAEs are reported measured in the absence of significant stimulus contamination at stimulus onset, providing for the identification of a TEOAE response beginning within the time window that is typically removed by windowing. Contrary to previous studies, it was found that in humans, as has previously been found in guinea pig, the TEOAE appears to arise from two generation mechanisms, the relative contributions of these two mechanisms being time and stimulus-level dependent. The method of windowing the earliest part of the ear canal measurement to remove stimulus artifact removes part of the TEOAE i.e., much of the component arising from a nonlinear generation mechanism. This reconciliation of TEOAE origin is consistent with all OAEs in mammals arising in a stimulus-level dependent manner from two mechanisms of generation, one linear, one nonlinear, as suggested by Shera and Guinan [J. Acoust. Soc. Am. 105, 782-798 (1999)].
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Affiliation(s)
- Robert H Withnell
- Department of Speech and Hearing Sciences, Indiana University, Bloomington, Indiana 47405, USA.
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Schairer KS, Ellison JC, Fitzpatrick D, Keefe DH. Use of stimulus-frequency otoacoustic emission latency and level to investigate cochlear mechanics in human ears. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2006; 120:901-14. [PMID: 16938978 PMCID: PMC1661834 DOI: 10.1121/1.2214147] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Stimulus frequency otoacoustic emission (SFOAE) sound pressure level (SPL) and latency were measured at probe frequencies from 500 to 4000 Hz and probe levels from 40 to 70 dB SPL in 16 normal-hearing adult ears. The main goal was to use SFOAE latency estimates to better understand possible source mechanisms such as linear coherent reflection, nonlinear distortion, and reverse transmission via the cochlear fluid, and how those sources might change as a function of stimulus level. Another goal was to use SFOAE latencies to noninvasively estimate cochlear tuning. SFOAEs were dominated by the reflection source at low stimulus levels, consistent with previous research, but neither nonlinear distortion nor fluid compression become the dominant source even at the highest stimulus level. At each stimulus level, the SFOAE latency was an approximately constant number of periods from 1000 to 4000 Hz, consistent with cochlear scaling symmetry. SFOAE latency decreased with increasing stimulus level in an approximately frequency-independent manner. Tuning estimates were constant above 1000 Hz, consistent with simultaneous masking data, but in contrast to previous estimates from SFOAEs.
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Affiliation(s)
- Kim S Schairer
- Center for Hearing Research, Boys Town National Research Hospital, 555 N. 30th Street, Omaha, Nebraska 68131, USA.
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