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Michael P Gorga - One of the best experts on this subject based on the ideXlab platform.
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do optimal conditions improve distortion product Otoacoustic Emission test performance
Ear and Hearing, 2011Co-Authors: Benjamin Kirby, Judy G Kopun, Stephen T Neely, Michael P GorgaAbstract:Objectives: To determine whether an “optimal” distortion product Otoacoustic Emission (DPOAE) protocol that (1) used optimal stimulus levels and primary-frequency ratios for each f2, (2) simultaneously measured 2f2 f1 and 2f1 f2 distortion products, (3) controlled source contribution, (4) implemented improved calibration techniques, (5) accounted for the influence of middle ear reflectance, and (6) applied multivariate analyses to DPOAE data results in improved accuracy in differentiating between normal-hearing and hearing-impaired ears, compared with a standard clinical protocol. Design: Data were collected for f2 frequencies ranging from 0.75 to 8 kHz in 28 normal-hearing and 78 hearing-impaired subjects. The protocol included a control condition incorporating standard stimulus levels and primary-frequency ratios calibrated with a standard SPL method and three experimental conditions using optimized stimuli calibrated with an alternative forward pressure level method. The experimental conditions differed with respect to the level of the reflection-source suppressor tone and included conditions referred to as the null suppressor (i.e., no suppressor tone presented), low-level suppressor (i.e., suppressor tone presented at 58 dB SPL), and high-level suppressor (i.e., suppressor tone presented at 68 dB SPL) conditions. The area under receiver operating characteristic (AROC) curves and sensitivities for fixed specificities (and vice versa) were estimated to evaluate test performance in each condition. Results: AROC analyses indicated (1) improved test performance in all conditions using multivariate analyses, (2) improved performance in the null suppressor and low suppressor experimental conditions compared with the control condition, and (3) poorer performance below 4 kHz with the high-level suppressor. As expected from AROC, sensitivities for fixed specificities and specificities for fixed sensitivities were highest for the null suppressor and low suppressor conditions and lowest for standard clinical procedures. The influence of 2f2 f1 and reflectance on test performance were negligible. Conclusions: Predictions of auditory status based on DPOAE measurements in clinical protocols may be improved by the inclusion of (1) optimized stimuli, (2) alternative calibration techniques, (3) low-level suppressors, and (4) multivariate analyses. (Ear & Hearing 2010;31;1–●)
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distortion product Otoacoustic Emission suppression tuning curves in humans
Journal of the Acoustical Society of America, 2011Co-Authors: Michael P Gorga, Judy G Kopun, Stephen T Neely, Hongyang TanAbstract:Distortion-product Otoacoustic Emission (DPOAE) suppression data as a function of suppressor level (L3) for f2 frequencies from 0.5 to 8 kHz and L2 levels from 10 to 60 dB sensation level were used to construct suppression tuning curves (STCs). DPOAE levels in the presence of suppressors were converted into decrement versus L3 functions, and the L3 levels resulting in 3 dB decrements were derived by transformed linear regression. These L3 levels were plotted as a function of f3 to construct STCs. When f3 is represented on an octave scale, STCs were similar in shape across f2 frequency. These STCs were analyzed to provide estimates of gain (tip-to-tail difference) and tuning (QERB). Both gain and tuning decreased as L2 increased, regardless of f2, but the trend with f2 was not monotonic. A roughly linear relation was observed between gain and tuning at each frequency, such that gain increased by 4–16 dB (mean ≈ 5 dB) for every unit increase in QERB, although the pattern varied with frequency. These findings suggest consistent nonlinear processing across a wide frequency range in humans, although the nonlinear operation range is frequency dependent.
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influence of calibration method on distortion product Otoacoustic Emission measurements ii threshold prediction
Ear and Hearing, 2010Co-Authors: Abigail R Rogers, Sienna R Burke, Judy G Kopun, Hongyang Tan, Stephen T Neely, Michael P GorgaAbstract:Objectives:Distortion-product Otoacoustic Emission (DPOAE) stimulus calibrations are typically performed in sound pressure level (SPL) before DPOAE measurements. These calibrations may yield unpredictable DPOAE response levels, presumably because of the presence of standing waves in the ear canal. F
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influence of in situ sound level calibration on distortion product Otoacoustic Emission variability
Journal of the Acoustical Society of America, 2008Co-Authors: Rachel A Scheperle, Judy G Kopun, Stephen T Neely, Michael P GorgaAbstract:Standing waves can cause errors during in-the-ear calibration of sound pressure level (SPL), affecting both stimulus magnitude and distortion-product Otoacoustic Emission (DPOAE) level. Sound intensity level (SIL) and forward pressure level (FPL) are two measurements theoretically unaffected by standing waves. SPL, SIL, and FPL in situ calibrations were compared by determining sensitivity of DPOAE level to probe-insertion depth (deep and “shallow”) for a range of stimulus frequencies (1–8 kHz) and levels (20–60 dB). Probe-insertion depth was manipulated with the intent to shift the frequencies with standing-wave minima at the Emission probe, introducing variability during SPL calibration. The absolute difference in DPOAE level between insertions was evaluated after correcting for an incidental change caused by the effect of ear-canal impedance on the Emission traveling from the cochlea. A three-way analysis of variance found significant main effects for stimulus level, stimulus frequency, and calibration method, as well as significant interactions involving calibration method. All calibration methods exhibited changes in DPOAE level due to the insertion depth, especially above 4 kHz. However, SPL demonstrated the greatest changes across all stimulus levels for frequencies above 2 kHz, suggesting that SIL and FPL provide more consistent measurements of DPOAEs for frequencies susceptible to standing-wave calibration errors.
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further efforts to predict pure tone thresholds from distortion product Otoacoustic Emission input output functions
Journal of the Acoustical Society of America, 2003Co-Authors: Michael P Gorga, Stephen T Neely, Patricia A Dorn, Brenda HooverAbstract:Recently, Boege and Janssen [J. Acoust. Soc. Am. 111, 1810–1818 (2002)] fit linear equations to distortion product Otoacoustic Emission (DPOAE) input/output (I/O) functions after the DPOAE level (in dB SPL) was converted into pressure (in μPa). Significant correlations were observed between these DPOAE thresholds and audiometric thresholds. The present study extends their work by (1) evaluating the effect of frequency, (2) determining the behavioral thresholds in those conditions that did not meet inclusion criteria, and (3) including a wider range of stimulus levels. DPOAE I/O functions were measured in as many as 278 ears of subjects with normal and impaired hearing. Nine f2 frequencies (500 to 8000 Hz in 12-octave steps) were used, L2 ranged from 10 to 85 dB SPL (5-dB steps), and L1 was set according to the equation L1=0.4L2+39 dB [Kummer et al., J. Acoust. Soc. Am. 103, 3431–3444 (1998)] for L2 levels up to 65 dB SPL, beyond which L1=L2. For the same conditions as those used by Boege and Janssen, we o...
Stephen T Neely - One of the best experts on this subject based on the ideXlab platform.
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do optimal conditions improve distortion product Otoacoustic Emission test performance
Ear and Hearing, 2011Co-Authors: Benjamin Kirby, Judy G Kopun, Stephen T Neely, Michael P GorgaAbstract:Objectives: To determine whether an “optimal” distortion product Otoacoustic Emission (DPOAE) protocol that (1) used optimal stimulus levels and primary-frequency ratios for each f2, (2) simultaneously measured 2f2 f1 and 2f1 f2 distortion products, (3) controlled source contribution, (4) implemented improved calibration techniques, (5) accounted for the influence of middle ear reflectance, and (6) applied multivariate analyses to DPOAE data results in improved accuracy in differentiating between normal-hearing and hearing-impaired ears, compared with a standard clinical protocol. Design: Data were collected for f2 frequencies ranging from 0.75 to 8 kHz in 28 normal-hearing and 78 hearing-impaired subjects. The protocol included a control condition incorporating standard stimulus levels and primary-frequency ratios calibrated with a standard SPL method and three experimental conditions using optimized stimuli calibrated with an alternative forward pressure level method. The experimental conditions differed with respect to the level of the reflection-source suppressor tone and included conditions referred to as the null suppressor (i.e., no suppressor tone presented), low-level suppressor (i.e., suppressor tone presented at 58 dB SPL), and high-level suppressor (i.e., suppressor tone presented at 68 dB SPL) conditions. The area under receiver operating characteristic (AROC) curves and sensitivities for fixed specificities (and vice versa) were estimated to evaluate test performance in each condition. Results: AROC analyses indicated (1) improved test performance in all conditions using multivariate analyses, (2) improved performance in the null suppressor and low suppressor experimental conditions compared with the control condition, and (3) poorer performance below 4 kHz with the high-level suppressor. As expected from AROC, sensitivities for fixed specificities and specificities for fixed sensitivities were highest for the null suppressor and low suppressor conditions and lowest for standard clinical procedures. The influence of 2f2 f1 and reflectance on test performance were negligible. Conclusions: Predictions of auditory status based on DPOAE measurements in clinical protocols may be improved by the inclusion of (1) optimized stimuli, (2) alternative calibration techniques, (3) low-level suppressors, and (4) multivariate analyses. (Ear & Hearing 2010;31;1–●)
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distortion product Otoacoustic Emission suppression tuning curves in humans
Journal of the Acoustical Society of America, 2011Co-Authors: Michael P Gorga, Judy G Kopun, Stephen T Neely, Hongyang TanAbstract:Distortion-product Otoacoustic Emission (DPOAE) suppression data as a function of suppressor level (L3) for f2 frequencies from 0.5 to 8 kHz and L2 levels from 10 to 60 dB sensation level were used to construct suppression tuning curves (STCs). DPOAE levels in the presence of suppressors were converted into decrement versus L3 functions, and the L3 levels resulting in 3 dB decrements were derived by transformed linear regression. These L3 levels were plotted as a function of f3 to construct STCs. When f3 is represented on an octave scale, STCs were similar in shape across f2 frequency. These STCs were analyzed to provide estimates of gain (tip-to-tail difference) and tuning (QERB). Both gain and tuning decreased as L2 increased, regardless of f2, but the trend with f2 was not monotonic. A roughly linear relation was observed between gain and tuning at each frequency, such that gain increased by 4–16 dB (mean ≈ 5 dB) for every unit increase in QERB, although the pattern varied with frequency. These findings suggest consistent nonlinear processing across a wide frequency range in humans, although the nonlinear operation range is frequency dependent.
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influence of calibration method on distortion product Otoacoustic Emission measurements ii threshold prediction
Ear and Hearing, 2010Co-Authors: Abigail R Rogers, Sienna R Burke, Judy G Kopun, Hongyang Tan, Stephen T Neely, Michael P GorgaAbstract:Objectives:Distortion-product Otoacoustic Emission (DPOAE) stimulus calibrations are typically performed in sound pressure level (SPL) before DPOAE measurements. These calibrations may yield unpredictable DPOAE response levels, presumably because of the presence of standing waves in the ear canal. F
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influence of in situ sound level calibration on distortion product Otoacoustic Emission variability
Journal of the Acoustical Society of America, 2008Co-Authors: Rachel A Scheperle, Judy G Kopun, Stephen T Neely, Michael P GorgaAbstract:Standing waves can cause errors during in-the-ear calibration of sound pressure level (SPL), affecting both stimulus magnitude and distortion-product Otoacoustic Emission (DPOAE) level. Sound intensity level (SIL) and forward pressure level (FPL) are two measurements theoretically unaffected by standing waves. SPL, SIL, and FPL in situ calibrations were compared by determining sensitivity of DPOAE level to probe-insertion depth (deep and “shallow”) for a range of stimulus frequencies (1–8 kHz) and levels (20–60 dB). Probe-insertion depth was manipulated with the intent to shift the frequencies with standing-wave minima at the Emission probe, introducing variability during SPL calibration. The absolute difference in DPOAE level between insertions was evaluated after correcting for an incidental change caused by the effect of ear-canal impedance on the Emission traveling from the cochlea. A three-way analysis of variance found significant main effects for stimulus level, stimulus frequency, and calibration method, as well as significant interactions involving calibration method. All calibration methods exhibited changes in DPOAE level due to the insertion depth, especially above 4 kHz. However, SPL demonstrated the greatest changes across all stimulus levels for frequencies above 2 kHz, suggesting that SIL and FPL provide more consistent measurements of DPOAEs for frequencies susceptible to standing-wave calibration errors.
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further efforts to predict pure tone thresholds from distortion product Otoacoustic Emission input output functions
Journal of the Acoustical Society of America, 2003Co-Authors: Michael P Gorga, Stephen T Neely, Patricia A Dorn, Brenda HooverAbstract:Recently, Boege and Janssen [J. Acoust. Soc. Am. 111, 1810–1818 (2002)] fit linear equations to distortion product Otoacoustic Emission (DPOAE) input/output (I/O) functions after the DPOAE level (in dB SPL) was converted into pressure (in μPa). Significant correlations were observed between these DPOAE thresholds and audiometric thresholds. The present study extends their work by (1) evaluating the effect of frequency, (2) determining the behavioral thresholds in those conditions that did not meet inclusion criteria, and (3) including a wider range of stimulus levels. DPOAE I/O functions were measured in as many as 278 ears of subjects with normal and impaired hearing. Nine f2 frequencies (500 to 8000 Hz in 12-octave steps) were used, L2 ranged from 10 to 85 dB SPL (5-dB steps), and L1 was set according to the equation L1=0.4L2+39 dB [Kummer et al., J. Acoust. Soc. Am. 103, 3431–3444 (1998)] for L2 levels up to 65 dB SPL, beyond which L1=L2. For the same conditions as those used by Boege and Janssen, we o...
Bradley Mcpherson - One of the best experts on this subject based on the ideXlab platform.
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ABO Blood Group and Cochlear Status: Otoacoustic Emission Markers.
Ear and hearing, 2018Co-Authors: Welen Weilu Chen, Kin Tsun Chow, Bradley McphersonAbstract:OBJECTIVES:There are an increasing number of research studies examining the effects of ABO blood group on susceptibility to disease. However, little is known regarding the potential relationship between blood group and hearing. Higher risk of noise-induced hearing loss was linked to blood group O in several occupational health studies. Based on this finding, a recent study of cochlear status was conducted with normal-hearing female participants representing equal numbers of the four blood groups in the ABO blood group system. ABO blood group was associated with cochlear characteristics, including the prevalence of spontaneous Otoacoustic Emissions (SOAEs) and the amplitudes of transient-evoked Otoacoustic Emissions (TEOAEs) and distortion-product Otoacoustic Emissions (DPOAEs). Females with blood group O showed significantly lower amplitudes of DPOAEs at some frequencies and lower prevalence of SOAEs compared with participants with blood group B. There was a general trend of reduced TEOAE and DPOAE amplitudes in blood group O individuals compared with participants with non-O blood groups. Following from this finding, and based on known sex differences in Otoacoustic Emission characteristics, the present study examined the possible effects of blood group on Otoacoustic Emission status in males. DESIGN:Sixty clinically normal-hearing males aged between 18 and 26 years, with equal numbers of participants in each of the ABO blood groups, were recruited by purposive sampling. SOAE, DPOAE, and linear and nonlinear TEOAE recordings were collected from all participants, as well as tympanometric data related to external and middle ear characteristics. RESULTS:The male blood group O participants exhibited significantly lower SOAE prevalence and reduced amplitudes of DPOAEs on average, and in the midfrequency range, than participants with blood group B, and lower nonlinear and linear TEOAE amplitudes at a number of frequencies when compared with participants with blood groups A and B. A consistent trend of lower TEOAE and DPOAE response amplitudes was observed in participants with blood group O. No significant difference was noted among blood groups for outer or middle ear characteristics. CONCLUSIONS:These results were consistent with previous findings of reduced Otoacoustic Emission responses in female blood group O individuals. Results support the hypothesis that blood group O individuals may be at increased risk of cochlear damage from noise exposure. Further investigation on the potential link between ABO blood group and auditory status, including potentially differential effects of noise exposure on cochlear function, is needed. The possible effects of ABO blood group on other aspects of audition, such as hearing sensitivity, speech understanding, and auditory processing, should be evaluated.
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neonatal Otoacoustic Emission screening and sudden infant death syndrome
International Journal of Pediatric Otorhinolaryngology, 2012Co-Authors: Rita S Y Chan, Bradley Mcpherson, Vicky W ZhangAbstract:Abstract Objective Exploratory research findings have suggested that Otoacoustic Emission (OAE) recordings may be predictive for infants at risk of sudden infant death syndrome (SIDS). The present study aimed to investigate whether an actual SIDS prevalence rate was comparable to OAE-determined rates for “at risk” status. Methods Previously collected OAE results from 521 infants in Hong Kong were used for analyses and OAE-determined “at risk” rate compared to the prevalence rate for SIDS in Hong Kong infants. Results Results indicated that the OAE-determined rates were very much greater than the actual prevalence of SIDS in Hong Kong. Conclusion The use of OAE screening to identify infants at risk for SIDS is therefore not advisable, using present criteria, as false alarm rates would be very high and this may cause unnecessary parental anxiety and a considerable additional burden to the health care system.
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outcomes of transient evoked Otoacoustic Emission testing in 6 year old school children a comparison with pure tone screening and tympanometry
International Journal of Pediatric Otorhinolaryngology, 2001Co-Authors: Carlie Driscoll, Joseph Kei, Bradley McphersonAbstract:Objectives: (1) To establish test performance measures for Transient Evoked Otoacoustic Emission testing of 6-year-old children in a school setting; (2) To investigate whether Transient Evoked Otoacoustic Emission testing provides a more accurate and effective alternative to a pure tone screening plus tympanometry protocol. Methods: Pure tone screening, tympanometry and transient evoked Otoacoustic Emission data were collected from 940 subjects (1880 ears), with a mean age of 6.2 years. Subjects were tested in non-sound-treated rooms within 22 schools. Receiver operating characteristics curves along with specificity, sensitivity, accuracy and efficiency values were determined for a variety of transient evoked Otoacoustic Emission/pure tone screening/tympanometry comparisons. Results: The Transient Evoked Otoacoustic Emission failure rate for the group was 20.3%. The failure rate for pure tone screening was found to be 8.9%, whilst 18.6% of subjects failed a protocol consisting of combined pure tone screening and tympanometry results. In essence, findings from the comparison of overall Transient Evoked Otoacoustic Emission pass/fail with overall pure tone screening pass/fail suggested that use of a modified Rhode Island Hearing Assessment Project criterion would result in a very high probability that a child with a pass result has normal hearing (true negative). However, the hit rate was only moderate. Selection of a signal-to-noise ratio (SNR) criterion set at greater than or equal to 1 dB appeared to provide the best test performance measures for the range of SNR values investigated. Test performance measures generally declined when tympanometry results were included, with the exception of lower false alarm rates and higher positive predictive values. The exclusion of low frequency data from the Transient Evoked Otoacoustic Emission SNR versus pure tone screening analysis resulted in improved performance measures. Conclusions: The present study poses several implications for the clinical implementation of Transient Evoked Otoacoustic Emission screening for entry level school children. Transient Evoked Otoacoustic Emission pass/fail criteria will require revision. The findings of the current investigation offer support to the possible replacement of pure tone screening with Transient Evoked Otoacoustic Emission testing for 6-year-old children. However, they do not suggest the replacement of the pure tone screening plus tympanometry battery. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.
Judy G Kopun - One of the best experts on this subject based on the ideXlab platform.
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do optimal conditions improve distortion product Otoacoustic Emission test performance
Ear and Hearing, 2011Co-Authors: Benjamin Kirby, Judy G Kopun, Stephen T Neely, Michael P GorgaAbstract:Objectives: To determine whether an “optimal” distortion product Otoacoustic Emission (DPOAE) protocol that (1) used optimal stimulus levels and primary-frequency ratios for each f2, (2) simultaneously measured 2f2 f1 and 2f1 f2 distortion products, (3) controlled source contribution, (4) implemented improved calibration techniques, (5) accounted for the influence of middle ear reflectance, and (6) applied multivariate analyses to DPOAE data results in improved accuracy in differentiating between normal-hearing and hearing-impaired ears, compared with a standard clinical protocol. Design: Data were collected for f2 frequencies ranging from 0.75 to 8 kHz in 28 normal-hearing and 78 hearing-impaired subjects. The protocol included a control condition incorporating standard stimulus levels and primary-frequency ratios calibrated with a standard SPL method and three experimental conditions using optimized stimuli calibrated with an alternative forward pressure level method. The experimental conditions differed with respect to the level of the reflection-source suppressor tone and included conditions referred to as the null suppressor (i.e., no suppressor tone presented), low-level suppressor (i.e., suppressor tone presented at 58 dB SPL), and high-level suppressor (i.e., suppressor tone presented at 68 dB SPL) conditions. The area under receiver operating characteristic (AROC) curves and sensitivities for fixed specificities (and vice versa) were estimated to evaluate test performance in each condition. Results: AROC analyses indicated (1) improved test performance in all conditions using multivariate analyses, (2) improved performance in the null suppressor and low suppressor experimental conditions compared with the control condition, and (3) poorer performance below 4 kHz with the high-level suppressor. As expected from AROC, sensitivities for fixed specificities and specificities for fixed sensitivities were highest for the null suppressor and low suppressor conditions and lowest for standard clinical procedures. The influence of 2f2 f1 and reflectance on test performance were negligible. Conclusions: Predictions of auditory status based on DPOAE measurements in clinical protocols may be improved by the inclusion of (1) optimized stimuli, (2) alternative calibration techniques, (3) low-level suppressors, and (4) multivariate analyses. (Ear & Hearing 2010;31;1–●)
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distortion product Otoacoustic Emission suppression tuning curves in humans
Journal of the Acoustical Society of America, 2011Co-Authors: Michael P Gorga, Judy G Kopun, Stephen T Neely, Hongyang TanAbstract:Distortion-product Otoacoustic Emission (DPOAE) suppression data as a function of suppressor level (L3) for f2 frequencies from 0.5 to 8 kHz and L2 levels from 10 to 60 dB sensation level were used to construct suppression tuning curves (STCs). DPOAE levels in the presence of suppressors were converted into decrement versus L3 functions, and the L3 levels resulting in 3 dB decrements were derived by transformed linear regression. These L3 levels were plotted as a function of f3 to construct STCs. When f3 is represented on an octave scale, STCs were similar in shape across f2 frequency. These STCs were analyzed to provide estimates of gain (tip-to-tail difference) and tuning (QERB). Both gain and tuning decreased as L2 increased, regardless of f2, but the trend with f2 was not monotonic. A roughly linear relation was observed between gain and tuning at each frequency, such that gain increased by 4–16 dB (mean ≈ 5 dB) for every unit increase in QERB, although the pattern varied with frequency. These findings suggest consistent nonlinear processing across a wide frequency range in humans, although the nonlinear operation range is frequency dependent.
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influence of calibration method on distortion product Otoacoustic Emission measurements ii threshold prediction
Ear and Hearing, 2010Co-Authors: Abigail R Rogers, Sienna R Burke, Judy G Kopun, Hongyang Tan, Stephen T Neely, Michael P GorgaAbstract:Objectives:Distortion-product Otoacoustic Emission (DPOAE) stimulus calibrations are typically performed in sound pressure level (SPL) before DPOAE measurements. These calibrations may yield unpredictable DPOAE response levels, presumably because of the presence of standing waves in the ear canal. F
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influence of in situ sound level calibration on distortion product Otoacoustic Emission variability
Journal of the Acoustical Society of America, 2008Co-Authors: Rachel A Scheperle, Judy G Kopun, Stephen T Neely, Michael P GorgaAbstract:Standing waves can cause errors during in-the-ear calibration of sound pressure level (SPL), affecting both stimulus magnitude and distortion-product Otoacoustic Emission (DPOAE) level. Sound intensity level (SIL) and forward pressure level (FPL) are two measurements theoretically unaffected by standing waves. SPL, SIL, and FPL in situ calibrations were compared by determining sensitivity of DPOAE level to probe-insertion depth (deep and “shallow”) for a range of stimulus frequencies (1–8 kHz) and levels (20–60 dB). Probe-insertion depth was manipulated with the intent to shift the frequencies with standing-wave minima at the Emission probe, introducing variability during SPL calibration. The absolute difference in DPOAE level between insertions was evaluated after correcting for an incidental change caused by the effect of ear-canal impedance on the Emission traveling from the cochlea. A three-way analysis of variance found significant main effects for stimulus level, stimulus frequency, and calibration method, as well as significant interactions involving calibration method. All calibration methods exhibited changes in DPOAE level due to the insertion depth, especially above 4 kHz. However, SPL demonstrated the greatest changes across all stimulus levels for frequencies above 2 kHz, suggesting that SIL and FPL provide more consistent measurements of DPOAEs for frequencies susceptible to standing-wave calibration errors.
Renata Sisto - One of the best experts on this subject based on the ideXlab platform.
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Modeling the dependence of the distortion product Otoacoustic Emission response on primary frequency ratio
Journal of the Association for Research in Otolaryngology, 2018Co-Authors: Renata Sisto, Sumitrajit Dhar, Uzma Shaheen Wilson, Arturo MoletiAbstract:When measured as a function of primary frequency ratio r = f _2/ f _1, using a constant f _2, distortion product Otoacoustic Emission (DPOAE) response demonstrates a bandpass shape, previously interpreted as the evidence for a cochlear “second filter.” In this study, an alternate, interference-based explanation, previously advanced in variants, is forwarded on the basis of experimental data along with numerical and analytical solutions of nonlinear and linear cochlear models. The decrease of the DPOAE response with increasing and decreasing ratios is explained by a diminishing “overlap” generation region and the onset of negative interference among wavelets of different phase, respectively. In this paper, the additional quantitative hypothesis is made that negative interference becomes the dominant effect when the spatial width of the generation (overlap) region exceeds half a wavelength of the DPOAE wavelets. Therefore, r is predicted to be optimal when this condition is matched. Additionally, the minimum on the low-ratio side of the DPOAE curve is predicted to occur as the overlap region width equals one wavelength. As the width of the overlap region depends on both tuning and ratio, while wavelength depends on tuning only, an experimental method for estimating tuning from either the width of the pass band or the optimal ratio of the DPOAE vs. ratio curve has been theoretically formulated and evaluated using numerical simulations. A linear model without the possibility of nonlinear suppression is shown to reasonably approximate data from human subjects at low ratios reinforcing the relevance of the proposed negative interference effect. The different dependence of the distortion and reflection DPOAE components on r as well as the nonmonotonic behavior of the distortion component observed at very low ratios are also in agreement with this interpretation.
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Otoacoustic Emission sensitivity to exposure to styrene and noise.
The Journal of the Acoustical Society of America, 2013Co-Authors: Renata Sisto, Luigi Cerini, Maria Pia Gatto, M. Gherardi, Andrea Gordiani, Filippo Sanjust, Enrico Paci, Giovanna Tranfo, Arturo MoletiAbstract:The ototoxic effect of the exposure to styrene is evaluated, also in the presence of simultaneous exposure to noise, using Otoacoustic Emissions as biomarkers of mild cochlear damage. Transient-evoked and distortion product Otoacoustic Emissions were recorded and analyzed in a sample of workers (15 subjects) exposed to styrene and noise in a fiberglass manufacturing facility and in a control group of 13 non-exposed subjects. Individual exposure monitoring of the airborne styrene concentrations was performed, as well as biological monitoring, based on the urinary concentration of two styrene metabolites, the Mandelic and Phenylglyoxylic acids. Noise exposure was evaluated using wearable phonometers, and hearing loss with pure tone audiometry. Due to their different job tasks, one group of workers was exposed to high noise and low styrene levels, another group to higher styrene levels, close to the limit of 20 ppm, and to low noise levels. A significant negative correlation was found between the Otoacoustic Emission levels and the concentration of the styrene urinary metabolites. Otoacoustic Emissions, and particularly distortion products, were able to discriminate the exposed workers from the controls, providing also a rough estimate of the slope of the dose-response relation between Otoacoustic levels and styrene exposure.
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transient evoked Otoacoustic Emission generators in a nonlinear cochlea
Journal of the Acoustical Society of America, 2012Co-Authors: A Moleti, Teresa Botti, Renata SistoAbstract:This study focuses on the theoretical prediction and experimental evaluation of the latency of transient-evoked Otoacoustic Emissions. Response components with different delay have been identified in several studies. The main generator of the transient response is assumed to be coherent reflection from cochlear roughness near the resonant place. Additional components of different latency can be generated by different mechanisms. Experimental data are re-analyzed in this study to evaluate the dependence of the latency on stimulus level, for each component of the response, showing that previous estimates of the Otoacoustic Emission latency were affected by systematic errors. The latency of the Emission from each generator changes very little with stimulus level, whereas their different growth rate causes sharp changes of the single-valued latency, estimated as the time of the absolute maximum of the bandpass filtered response. Results of passive linear models, in which gain and bandwidth of the cochlear amplifier are strictly related, are incompatible with the observations. Although active linear models including delayed stiffness terms do predict much slower dependence of latency on the stimulus level, a suitable nonlinear model should be designed, capable of decoupling more effectively the dependence on stimulus level of amplitude and phase of the Otoacoustic response.
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transient evoked Otoacoustic Emission latency and cochlear tuning at different stimulus levels
Journal of the Acoustical Society of America, 2007Co-Authors: Renata Sisto, A MoletiAbstract:Cochlear latency has been evaluated in young adults by time-frequency analysis of transient evoked Otoacoustic Emissions recorded using the nonlinear acquisition mode at different levels of the click stimulus. Objective, even if model-dependent, estimates of cochlear tuning have been obtained from the Otoacoustic latency estimates. Transmission-line cochlear models predict that the transient-evoked Otoacoustic Emission latency is dependent on the stimulus level, because the bandwidth of the cochlear filter (tuning) depends on the local cochlear excitation level due to nonlinear damping. The results of this study confirm the increase of tuning with increasing frequency and show clearly the decrease of latency and tuning with increasing stimulus level. This decrease is consistent with the expected relation between the slowing down of the traveling wave near the tonotopic place and the cochlear excitation amplitude predicted by cochlear models including nonlinear damping. More specifically, these results support the models in which nonlinear damping consists of a quadratic term and a constant positive term.
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Otoacoustic Emission sensitivity to low levels of noise induced hearing loss
Journal of the Acoustical Society of America, 2007Co-Authors: Renata Sisto, Silvia Chelotti, Lido Moriconi, Stefania Pellegrini, Angela Citroni, Valeria Monechi, Rosa Gaeta, Iole Pinto, Nicola Stacchini, A MoletiAbstract:With the aim of investigating the capability of Otoacoustic Emission (OAE) in the detection of low levels of noise-induced hearing loss, audiometric and Otoacoustic data of young workers (age: 18–35) exposed to different levels of industrial noise have been recorded. These subjects are participating in a long-term longitudinal study, in which audiometric, exposure (both professional and extra-professional), and OAE data (transient evoked and distortion product) will be collected for a period of several years. All measurements have been performed, during routine occupational health surveillance, with a standard clinical apparatus and acquisition procedure, which can be easily used in the occupational safety practice. The first study was focused on the correlation between transient evoked OAE signal-to-noise ratio and distortion product (DPOAE) OAE level and the audiometric threshold, investigating the causes of the rather large intersubject variability of the OAE levels. The data analysis has shown that, i...
