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Measurement of distortion product otoacoustic emissions in South African gold miners at risk for noise-induced hearing loss.Edwards, Anita Lynne 26 February 2010 (has links)
Background
The noise-exposed population in the mining industry in South Africa poses unique
problems to the occupational audiologist working in this environment, due to the
broad linguistic and cultural diversity in the audiology and mining environment.
Unfortunately, the problems are also exacerbated by a high incidence of
pseudohypacusis within this population who are incentivised by compensation for
NIHL. A solution to these specific problems would be the reliable and valid use of
an objective test of function such as the DPOAE. The rationale for the study
therefore was to extend the body of knowledge about the use of DPOAEs in the
noise-exposed mining population.
Methodology
The current study was divided into two phases: phase one’s objectives entailed the
investigation of the characteristics of DPOAEs in a noise-exposed mining
population; phase two aimed to develop a multivariate regression model that would
facilitate the prediction of the hearing threshold levels from the DPOAE levels in
this population.
Objectives
The objectives in phase one of the study were to investigate the bivariate
correlations between DPOAE levels and air-conduction hearing threshold levels in
noise-exposed gold miners, for the three stimulus procedures. The study also
aimed to investigate the bivariate correlations between various pure-tone averages
(PTA) and the DPOAE averages of f2 frequencies closest to those pure-tone
frequencies. Similarly, the Speech Recognition Thresholds (SRT) were correlated
with DPOAE averages of f2 frequencies closest to the PTA.
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The study further aimed to investigate the characteristics of DPOAEs in noiseexposed
gold miners by comparing the average DPOAE levels for different age
category groups, different ethnic groups and for different occupation types. Finally,
phase one aimed to describe the characteristics of emission level and noise floor
differences (DP-NF) in a DPOAE database of a noise-exposed gold mining
population.
Phase two of the study had the objective of developing a multivariate prediction
model using stepwise regression analysis to identify which of the DPOAE
frequencies produced the best prediction of the audiogram frequencies when
multivariate inputs were used for each stimulus procedure. The objective was also
to evaluate the use of the predicted audiograms’ calculated percentage loss of
hearing (PLH) with that of the actual PLH.
This retrospective record review used an audiological database from a mine in the
North West province of South Africa that contained 4800 records. The required
sample size to be representative of the population was statistically determined. The
records were randomly selected resulting a sample size for the FB2-S group of
161, for the FB1-S group of 177 and the FB1-S group of 155 respectively. The
hearing loss characteristics in the samples ranged from normal to profound losses
with the majority being mild to moderate hearing losses.
Results
The findings of phase one showed negative correlations ranging from -0.327 to
-0.573 for Frequency Band 1- Replicated (FB1-R) between DPOAE levels and air
conduction hearing threshold levels. Similarly, Frequency Band 1-Single (FB1-S)
and Frequency Band 2-Single (FB2-S) also showed negative correlations (ranging
from -0.203 to -0.609 and -0.274 to -0.738 respectively). These correlation
strengths have been confirmed previously by other published studies.
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Correlations between groups of frequencies on an audiogram and averaged match
groups of DPOAE frequencies by intensity levels, both for PTA and SRT, ranged
between -0.323 and -0.661. No statistically significant differences were found
between the DPOAE measurements and ethnic groups of African and Caucasian
(Sample size of 175 for FB1-S, 137 for FB1-R and 161 for FB2-S). No differences
were found between the DPOAE levels and the occupation types of mining team
members, stopers and drillers. There was, however, a relational finding of a
progressive decrement of DPOAE intensity levels by decade of age increase
(Sample size of 37 for FB1-S, 45 for FB1-R and 155 for FB2-S).
Mean DP levels in this population ranged from 1.5 to -14 dB SPL, and mean NF
levels in the sample ranged from 0.1 to -16.8 dB SPL with the mean DP-NF
difference ranges form 0.4 to 9.3 dBSPL. More than 60% of the data collected
resulted in a DP-NF of less than 10 dB SPL.
The simple correlation relationship between hearing threshold levels and DPOAEs
did not sufficiently explain the variance within the sample and due to the fact that a
number of the independent variables in the sample were highly correlated, there
was a call to use a method that allows for multicolinearity (i.e. stepwise regression
analysis) in order to develop a prediction model. Consequently, phase two of the
study was able to compare actual air-conduction hearing threshold levels with
those calculated with the prediction model, and then calculate predicted
percentage loss of hearing (PLH) with actual PLH found in the noise-exposed gold
miners.
In phase two, with the use of the predictive models, the predicted hearing threshold
levels were found to differ from the actual thresholds by no more than 7dB HL
across all frequencies (average of 5 dB HL for FB1-R, 2 dB HL for FB1-S and 3 dB
HL for FB2-S). The differences for each audiogram frequency between the actual
and the predicted thresholds are represented on scatter plots in phase two of the
thesis. The PLH of the predicted audiograms was calculated using the weighted
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tables prescribed by the Compensation for Occupational Diseases and Injuries Act
(COIDA). A comparison of the predicted PLH with the actual PLH indicated that the
predicted PLH ranged between minus 1.3% PLH and plus 6.7% PLH of the actual
PLH.
Results of the study are discussed with regards to the clinical implications, and the
implications for training occupational audiologists in South Africa. The results of
this study will improve and inform practice in the mining environment and in the
field of compensation for NIHL. By developing a reliable prediction tool which is
implemented on an objective test proven to document the extent of damage
incurred from noise-exposure, a clinician will gain greater confidence in an
accurate diagnosis, thereby further safeguarding a vulnerable population. The
results from this study are highly relevant to the mining industry and will add value
to the industrial development of South Africa by informing the policy on hearing
conservation and compensation, thereby increasing the awareness of the need for
improved occupational health and safety conditions and sustainable development
in the mining industry.
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The fine structure of distortion product otoacoustic emissions: the primary originDu, Yafei 07 August 2003 (has links)
No description available.
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The Effect of Noise on DPOAEs and Pure-tone ThresholdsWest, A. D., Burks, Christopher A., Foren, D., Fagelson, Marc A. 01 November 2002 (has links)
No description available.
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Protocols of DPOAE Measurements Aimed at Reducing Test TimeSmurzynski, Jacek, Janssen, Thomas 05 March 2015 (has links)
Routine clinical distortion product otoacoustic emission (DPOAE) tests use monaural sequential presentation of primary tones. To reduce testing time, multiple DPOAEs (mDPOAEs) can be measured by stimulating the ear with two tone pairs simultaneously. Moreover, both ears can be tested at the same time with a portable device, Sentiero (PATH medical GmbH), equipped with two sound probes. The purpose of the study was to evaluate whether mDPOAE measurements can be done in both ears simultaneously without mutual influence of primary tone pairs in the ipsilateral and the contralateral ear. Data were collected in 20 normal-hearing young adults. The DP-grams were obtained for seven f2- frequencies varying in the 1.5-8-kHz range with the level L2 set at 65 and 45 dB SPL, whereas the level L1 was adjusted according to the scissor paradigm. For each subject, a set of DP-gram data was collected using single- and multi-frequency presentations of the primaries for both monaural and binaural conditions. The mean DPOAE and noise levels collected with mDPOAE and binaural presentation conditions were highly reproducible when compared to those obtained with the single-frequency monaural paradigm. Thus, multi-frequency and binaural measurements could be applied to reduce DPOAE testing time considerably.
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DPOAEs in Normally Hearing Patients with Either Unilateral or Bilateral TinnitusSmurzynski, Jacek 11 February 2011 (has links)
No description available.
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Influence of Unilateral Tinnitus on Distortion Product Otoacoustic Emission LevelsSmurzynski, Jacek, Fabijanska, Anna, Kochanek, Krzysztof, Skarzynski, Henryk, Skarzynski, Henryk 08 June 2009 (has links)
It has been suggested that the presence of a limited area of damaged outer hair cells (OHCs) with intact inner hair cells, which may not be detected on the conventional audiogram, results in unbalanced neural activity between Type I and Type II fibers leading to tinnitus. In normal-hearing tinnitus patients, DPOAEs provided ambiguous data of OHC function when compared to non-tinnitus controls. Hearing loss in the extended high-frequency (EHF) region may decrease DPOAEs evoked at lower frequencies. Results of EHF audiometry in tinnitus patients are limited. The aim of the study was to evaluate DPOAEs and EHF thresholds in normal-hearing patients reporting unilateral tinnitus in left ear. Thus, each subject acted as their own control.
Data were obtained for 26 subjects with bilateral hearing thresholds10, 12.5, 14, and 16 kHz. The DP-grams were measured in the 0.5-8 kHz range using 65/55-dB SPL primaries and f2/f1=1.2. The data analyses included DPOAEs with S/N>3 dB.
Median audiometric data showed that thresholds in the left ears were significantly higher than those in the right ears at all four EHFs. Mean DPOAE levels of the left ears were lower than those of the right ears in the frequency range above 1 kHz. Additionally, a paired-comparison test of DPOAE levels of each patient’s right and left ear revealed significant differences at 6 and 8 kHz.
The results indicate that: 1. OHC impairment in the most basal region reduces contribution to more apically generated DPOAEs; 2. OHC impairment in a limited area, which may be revealed by DPOAEs but not by conventional audiometry, can contribute to tinnitus generation; and 3. patients with unilateral tinnitus and normal hearing on the conventional audiogram are likely to demonstrate hearing loss in the EHF region.
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Influence of Low- and Ultra High-frequency Hearing Thresholds on Distortion Product Otoacoustic Emissions (DPOAEs): An Attempt to Separate DPOAE Generation MechanismsSmurzynski, Jacek 01 January 2010 (has links)
No description available.
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The Influence of High Frequency Hearing Loss on the Distortion Product Otoacoustic Emissions in Tinnitus Subjects with Normal Hearing Thresold (0,25-8kHz)Fabijańska, Anna, Smurzynski, Jacek, Kochanek, Krzysztof, Bartnik, Grazyna, Raj-Koziak, Danuta, Skarzynski, Henryk 01 January 2012 (has links)
Aim of the study: To evaluate the influence of high frequency hearing loss (>8000 Hz) on distortion product otoacoustic emissions registered in the frequency range from 0,5 to 8 kHz.
Material and methods: 280 ears with tinnitus and normal hearing (0.25–8 kHz) divided into 3 groups depending on the degree of high frequency hearing loss: group A – hearing threshold up to 20 dB for 10, 12.5, 14 and 16 kHz (68 ears); group B – hearing threshold 25–40 dB HLfor at least one of four EHfs (93 ears); group C – hearing threshold above 40 dB HL for at least one of four EHFs (119 ears). For each group mean audiogram and DP-gram were obtained and statistical analysis was used for comparison across these groups.
Results: Mean DPOAE values in group C were significantly lower in comparison with group A for the frequency range 2–8 kHz, and in comparison with group B were significantly lower for the frequency range 4–8 kHz.
Conclusions: High frequency hearing loss (above 8 kHz) has a relevant influence on distortion product otoacoustic emissions registered at frequencies below 8 kHz in tinnitus patients. The greater is hearing loss above 8 kHz, the lower is DPOAE value below 8 kHz.
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Modulation von Distorsionsprodukt-Otoemissionen duch Töne tiefer FrequenzHirschfelder, Anke 24 July 2001 (has links)
Die Modulation von Distorsionsprodukt-Otoemissionen (DPOAE) durch Töne tiefer Frequenz ist ein Methode, mit der die Auswirkung von Verlagerungen der kochleären Trennwand auf die Funktion des kochleären Verstärkers untersucht werden kann. Damit bietet sie einen neuen objektiven Ansatz zur Diagnostik unterschiedlicher kochleärer Hörstörungen sowie zur Untersuchung physiologischer Mechanismen der Kochlea. Durch einen tieffrequenten Ton (f = 32,8 Hz) werden die DPOAE in Abhängigkeit von dessen Phase periodisch verändert. Die Ausprägung der Modulation hängt von den Parametern des Tieftons und der Primärtöne (mit den Frequenzen f1 und f2) ab. Bei zwölf normalhörenden Probanden wird der Einfluß des Tieftonpegels, der Primärtonpegel und der Primärtonfrequenzen auf die Modulation der DPOAE mit der Frequenz 2f1-f2 untersucht. Die Ergebnisse dieser Methode werden mit denen der subjektiven Phasenaudiometrie bei diesen Probanden verglichen. Mit den Primärtonfrequenzen f1 = 2,5 und f2 = 3 kHz steigt die mittlere Modulationstiefe der DPOAE mit zunehmendem Tieftonpegel sowie mit abnehmenden Primärtonpegeln nichtlinear. Mit hohem Tieftonpegel (L = 115 dB SPL) und geringen Primärtonpegeln (bis zu L1 = 50 und L2 = 30 dB HL) sind DPOAE-Pegelverläufe mit zwei Minima und zwei Maxima pro Tieftonperiode zu beobachten. Die Pegelminima liegen kurz nach der maximalen Druck- bzw. Sogphase des Tieftons vor dem Trommelfell, entsprechend der maximalen Auslenkung der kochleären Trennwand in Richtung Scala vestibuli bzw. Scala tympani. Sie zeigen eine mittlere Latenz von 4 ms gegenüber den Verdeckungsmaxima der subjektiven Mithörschwelle im Phasenaudiogramm, die wahrscheinlich durch die Summe der Antwortzeit der aktiven kochleären Prozesse und der Laufzeit der DPOAE-Signale retrograd aus der Kochlea zur Meßsonde im äußeren Gehörgang zustande kommt. Mit geringeren Tieftonpegeln (L = 110 dB SPL) bzw. höheren Primärtonpegeln (ab L1 = 55 und L2 = 40 dB HL) sowie höheren Primärtonfrequenzen (f1 = 4, f2 = 4,8 kHz) sind nur noch jeweils ein DPOAE-Pegelminimum und -maximum pro Tieftonperiode zu beobachten. Mit den Primärtonfrequenzen f1 = 5 und f2 = 6 kHz zeigt sich keine Modulation der DPOAE mehr. Die Ergebnisse werden unter Verwendung einer Boltzmannfunktion zweiter Ordnung als Annäherung an die mechano-elektrische Transferfunktion äußerer Haarzellen simuliert. Bei einigen Probanden werden außerdem die Modulation der DPOAE mit der Frequenz 3f1-2f2 durch den tieffrequenten Ton sowie der Einfluß spontaner otoakustischer Emissionen (SOAE) auf die Messung tieftonmodulierter DPOAE untersucht. / Low-frequency modulation of distortion product otoacoustic emissions (DPOAE) is a method which allows to investigate the effect of the displacement of the cochlear partition on the function of the active cochlear process. It offers a new objective approach to diagnose different sensory hearing disorders as well as to investigate physiological cochlear mechanisms. The DPOAE are modulated by a low-frequency tone (with the frequency f = 32,8 Hz), depending on its phase. The extent of this modulation depends on the acoustic parameters of the suppressing low-frequency tone and the stimulating primary tones (f1 and f2). In twelve normal hearing subjects the influence of the low-frequency tone level, the levels and the frequencies of the primary tones on the modulation of the DPOAE with the frequency 2f1-f2 are investigated. In these subjects, the phase-dependent masked subjective threshold is also registered. The results of both methods are compared. With the primary tone frequencies f1 = 2,5 and f2 = 3 kHz the mean value of the DPOAE modulation depth presents a nonlinear growth with increasing low-frequency tone level and decreasing primary tone levels, respectively. With high low-frequency tone level (L = 115 dB SPL) and low primary tone levels (up to L1 = 55 and L2 = 40 dB HL), the time course of the DPOAE level shows two minima and two maxima within one period of the low-frequency tone. The minimal DPOAE levels are registered shortly after the phases of maximal condensation and rarefaction of the low-frequency tone in front of the eardrum, respectively, corresponding to the largest displacement of the cochlear partition towards the scala tympani and the scala vestibuli. The time course of the DPOAE level shows a mean latency of 4 ms with regard to the masking patterns of the phase-dependent masked threshold, due to the response time of the active cochlear process and the retrograde travelling time of the DPOAE. With lower low-frequency tone levels (L1 = 110 dB SPL), higher primary tone levels (from L1 = 55, L2 = 40 dB HL), and higher primary tone frequencies (f1 = 4, f2 = 4,8 kHz), respectively, the DPOAE level presents only one maximum and one minimum per period of the low-frequency tone. With the primary frequencies f1 = 5 and f2 = 6 kHz no modulation of the DPOAE is registered. The results are simulated using a second-order Boltzmann function as an approximation of the mechano-electric transfer function of the outer hair cells. Additionally, in some subjects the low-frequency modulation of the DPOAE with the frequency 3f1-2f2 and the influence of spontaneous otoacoustic emissions (SOAE) on the registration of low-frequency modulated DPOAE are investigated.
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Extended High-frequency Audiometry and Distortion Product Otoacoustic Emissions in Normal-hearing Patients with Unilateral TinnitusSmurzynski, Jacek, Fabijanska, Anna, Kochanek, Krzysztof, Skarzynski, Henryk 24 June 2009 (has links)
Some tinnitus patients have normal hearing on the conventional audiogram. It has been suggested that the presence of a limited area of damaged outer hair cells (OHCs) with intact inner hair cells, which is not detected on the audiogram, results in unbalanced neural activity between Type I and Type II fibers leading to tinnitus. Distortion product otoacoustic emissions (DPOAEs) provided ambiguous data of OHC function in normal-hearing tinnitus patients when compared to non-tinnitus controls. It is known that hearing loss in the extended high frequency (EHF) region may decrease DPOAEs evoked at lower frequencies. Results of EHF audiometry in tinnitus patients are limited. The aim of the study was to evaluate DPOAEs and EHF thresholds in normal-hearing patients reporting unilateral tinnitus in left ear. Thus, each subject acted as their own control. Data were obtained for 25 subjects with bilateral hearing thresholds 3dB. Median audiometric data showed that thresholds in the left ears were significantly higher than those in the right ears at all four EHFs. Mean DPOAE levels of the left ears were lower than those of the right ears in the frequency range above 1 kHz. Additionally, a paired-comparison test of DPOAE levels of each patient’s right and left ear revealed significant differences at 6, and 8 kHz. The results indicate that: 1. OHC impairment in the most basal region reduces contribution to more apically generated DPOAEs; 2. OHC impairment in a limited area, which may be revealed by DPOAEs but not by conventional audiometry, can contribute to tinnitus generation; and 3. patients with unilateral tinnitus and normal hearing on the conventional audiogram are likely to demonstrate hearing loss in the EHF region.
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