Cochlear Sources and Otoacoustic Emissions

2010 ◽  
Vol 21 (03) ◽  
pp. 176-186 ◽  
Author(s):  
Tiffany A. Johnson
Keyword(s):  
Fine Structure ◽  
Otoacoustic Emissions ◽  
Stimulus Frequency ◽  
Normal Hearing ◽  
Clinical Applications ◽  
Clinical Test ◽  
Similar Amount ◽  
Distortion Product ◽  
Stimulus Parameters ◽  
Coherent Reflection

Current understanding suggests that there are two different mechanisms by which otoacoustic emissions (OAEs) are generated in the cochlea. These mechanisms include a nonlinear-distortion mechanism and a coherent-reflection mechanism. Distortion product OAEs (DPOAEs) are believed to include contributions from both mechanisms, while stimulus frequency OAEs (SFOAES), at least at low and moderate levels, are believed to be generated primarily by the coherent-reflection mechanism. In the case of DPOAEs, the interaction of the two mechanisms produces a series of alternating peaks and valleys in the response level when recorded in small frequency increments. This pattern of peaks and valleys typically is referred to as fine structure. There has been much speculation that the interaction of the two mechanisms and the resulting fine structure limits the clinical test performance of DPOAEs. There are few data to address this speculation. Here, we review the literature that describes the cochlear source mechanisms and their potential relationship to clinical applications. We then present results for preliminary data collected in a group of 10 normal-hearing subjects where we explore the influence of common approaches to setting DPOAE stimulus parameters on the resulting fine structure. These preliminary results suggest that, at the moderate stimulus levels used in clinical applications, each of the different stimulus parameters results in a similar amount of fine structure and, therefore, fine structure cannot be eliminated through manipulation of stimulus parameters. We also review the results of some preliminary efforts to identify stimulus parameters that can be used to record SFOAEs (OAEs generated by the reflection mechanism). The potential clinical applications of SFOAEs have received little attention in the literature. By identifying stimulus parameters producing robust responses in normal-hearing ears, it may be possible to more fully evaluate clinical applications of SFOAEs.

Exploring Optimal Stimulus Frequency Ratio for Measurement of the Quadratic f 2 –f 1 Distortion Product Otoacoustic Emission in Humans

2018 ◽  
Vol 61 (7) ◽  
pp. 1794-1806
Author(s):  
Rachael R. Baiduc ◽  
Sumitrajit Dhar
Keyword(s):  
Otoacoustic Emissions ◽  
Endolymphatic Hydrops ◽  
Stimulus Frequency ◽  
Otoacoustic Emission ◽  
Normal Hearing ◽  
Distortion Product Otoacoustic Emission ◽  
Clinical Implementation ◽  
Distortion Product ◽  
Recent Interest ◽  
Stimulus Parameters

Purpose Distortion product otoacoustic emissions (DPOAEs) are a by-product of active cochlear processes that lead to the compressive nonlinearity of healthy ears. The most commonly studied emission is at the frequency 2f 1 –f 2 , but there has been recent interest in using the quadratic distortion product at the frequency f 2 –f 1 to detect cochleopathies including endolymphatic hydrops. Before the DPOAE at f 2 –f 1 can be applied clinically in any capacity, optimal stimulus parameters for its elicitation must be established. Method We investigated stimulus parameters for the DPOAEs at f 2 –f 1 and 2f 1 –f 2 in 23 adults with normal hearing. Logarithmically swept tones between approximately 0.6 and 20 kHz (L 1 = L 2 = 70 dB SPL) served as the higher frequency stimulus (f 2 ). DPOAEs were measured for 6 f 2 /f 1 ratios: 1.14, 1.18, 1.22, 1.30, 1.32, and 1.36. Results Both DPOAEs were consistently measurable. In line with previous investigations, the highest levels of the DPOAE at 2f 1 –f 2 were generated between f 2 /f 1 ratios of 1.14–1.22, with a peak in the level ratio function at 1.22. In contrast, f 2 –f 1 was less influenced by ratio, although the narrowest ratio (1.14) produced slightly higher levels across frequency. Conclusion The DPOAE at f 2 –f 1 is measurable in individuals with normal hearing up to f 2 of 20 kHz at narrow f 2 /f 1 ratios. Measurements at additional stimulus levels and in subjects with hearing impairment will be needed before clinical implementation.

Detection of Hearing Loss Using 2f2-f1 and 2f1-f2 Distortion-Product Otoacoustic Emissions

2005 ◽  
Vol 48 (5) ◽  
pp. 1165-1186 ◽  
Author(s):  
Tracy S. Fitzgerald ◽  
Beth A. Prieve
Keyword(s):  
Otoacoustic Emissions ◽  
Signal To Noise Ratio ◽  
Normal Hearing ◽  
Hearing Impaired ◽  
Distortion Product Otoacoustic Emissions ◽  
Signal To Noise ◽  
Primary Level ◽  
Distortion Product ◽  
Hearing Status ◽  
Stimulus Parameters

Although many distortion-product otoacoustic emissions (DPOAEs) may be measured in the ear canal in response to 2 pure tone stimuli, the majority of clinical studies have focused exclusively on the DPOAE at the frequency 2f1-f2. This study investigated another DPOAE, 2f2-f1, in an attempt to determine the following: (a) the optimal stimulus parameters for its clinical measurement and (b) its utility in differentiating between normal-hearing and hearing-impaired ears at low-to-mid frequencies (≤2000 Hz) when measured either alone or in conjunction with the 2f1-f2 DPOAE. Two experiments were conducted. In Experiment 1, the effects of primary level, level separation, and frequency separation (f2/f1) on 2f2-f1 DPOAE level were evaluated in normal-hearing ears for low-to-mid f2 frequencies (700–2000 Hz). Moderately high-level primaries (60–70 dB SPL) presented at equal levels or with f2 slightly higher than f1 produced the highest 2f2-f1 DPOAE levels. When the f2/f1 ratio that produced the highest 2f2-f1 DPOAE levels was examined across participants, the mean optimal f2/f1 ratio across f2 frequencies and primary level separations was 1.08. In Experiment 2, the accuracy with which DPOAE level or signal-to-noise ratio identified hearing status at the f2 frequency as normal or impaired was evaluated using clinical decision analysis. The 2f2-f1 and 2f1-f2 DPOAEs were measured from both normal-hearing and hearing-impaired ears using 2 sets of stimulus parameters: (a) the traditional parameters for measuring the 2f1-f2 DPOAE (f2/f1 = 1.22; L1, L2 = 65, 55 dB SPL) and (b) the new parameters that were deemed optimal for the 2f2-f1 DPOAE in Experiment 1 (f2/f1 = 1.073, L1 and L2 = 65 dB SPL). Identification of hearing status using 2f2-f1 DPOAE level and signal-to-noise ratio was more accurate when the new stimulus parameters were used compared with the results achieved when the 2f2-f1 DPOAE was recorded using the traditional parameters. However, identification of hearing status was less accurate for the 2f2-f1 DPOAE measured using the new parameters than for the 2f1-f2 DPOAE measured using the traditional parameters. No statistically significant improvements in test performance were achieved when the information from the 2 DPOAEs was combined, either by summing the DPOAE levels or by using logistic regression analysis.

scholarly journals Early Indices of Reduced Cochlear Function in Young Adults with Type-1 Diabetes Revealed by DPOAE Fine Structure

2019 ◽  
Vol 30 (06) ◽  
pp. 459-471 ◽  
Author(s):  
Christopher Spankovich ◽  
Glenis R. Long ◽  
Linda J. Hood
Keyword(s):  
Type 1 Diabetes ◽  
Young Adults ◽  
Fine Structure ◽  
Otoacoustic Emissions ◽  
Normal Hearing ◽  
Cochlear Function ◽  
Hearing Sensitivity ◽  
Distortion Product ◽  
Type 1 Dm

AbstractThe relationship between type-1 diabetes mellitus (DM) and cochlear dysfunction remains inconclusive.The purpose of this study was to examine otoacoustic emissions (OAEs) in normal-hearing young adults with type-1 DM as compared with matched controls and identify potential covariates influencing OAE findings.Cross-sectional study.N = 40 young adults aged 18–28 years including individuals with type-1 DM (n = 20) and age–gender matched controls (n = 20) with normal hearing sensitivity.Measures of pure-tone threshold sensitivity and OAEs, including distortion product otoacoustic emissions (DPOAEs), transient evoked OAEs, and DPOAE fine structure, were compared between groups. Covariates such as noise exposure and DM-related factors (e.g., duration of disease, glycated hemoglobin levels) were considered. Statistical analysis included analysis of variance and linear regression.Measures of hearing sensitivity and auditory function in both groups were comparable for all assays, except DPOAE fine structure. A reduced number of fine structure peaks and component amplitudes were found in the type-1 diabetes DM group with the primary difference in the reflection component.The results indicate that reduced cochlear function in young adults with type-1 DM can be revealed using DPOAE fine structure, suggesting potential clinical applications of DPOAE fine structure in early identification of cochlear pathology. Potential factors underlying these findings are discussed.

Evaluation of Efferent Auditory System and Hearing Quality in Parkinson's Disease: Is the Difficulty in Speech Understanding in Complex Listening Conditions Related to Neural Degeneration or Aging?

2020 ◽  
pp. 1-9
Author(s):  
Nuriye Yıldırım Gökay ◽  
Bülent Gündüz ◽  
Fatih Söke ◽  
Recep Karamert
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Auditory System ◽  
Otoacoustic Emissions ◽  
Pure Tone ◽  
Pure Tone Audiometry ◽  
Auditory Pathway ◽  
Normal Hearing ◽  
System Function ◽  
Distortion Product

Purpose The effects of neurological diseases on the auditory system have been a notable issue for investigators because the auditory pathway is closely associated with neural systems. The purposes of this study are to evaluate the efferent auditory system function and hearing quality in Parkinson's disease (PD) and to compare the findings with age-matched individuals without PD to present a perspective on aging. Method The study included 35 individuals with PD (mean age of 48.50 ± 8.00 years) and 35 normal-hearing peers (mean age of 49 ± 10 years). The following tests were administered for all participants: the first section of the Speech, Spatial and Qualities of Hearing Scale; pure-tone audiometry, speech audiometry, tympanometry, and acoustic reflexes; and distortion product otoacoustic emissions (DPOAEs) and contralateral suppression of DPOAEs. SPSS Version 25 was used for statistical analyses, and values of p < .05 were considered statistically significant. Results There were no statistically significant differences in the pure-tone audiometry thresholds and DPOAE responses between the individuals with PD and their normal-hearing peers ( p = .732). However, statistically significant differences were found between the groups in suppression levels of DPOAEs and hearing quality ( p < .05). In addition, a statistically significant and positive correlation was found between the amount of suppression at some frequencies and the Speech, Spatial and Qualities of Hearing Scale scores. Conclusions This study indicates that medial olivocochlear efferent system function and the hearing quality of individuals with PD were affected adversely due to the results of PD pathophysiology on the hearing system. For optimal intervention and follow-up, tasks related to hearing quality in daily life can also be added to therapies for PD.

Early Evidence of Cochlear Damage in a Large Sample of Percussionists

2005 ◽  
Vol 20 (3) ◽  
pp. 135-139
Author(s):  
Jodee A Pride ◽  
David R Cunningham
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Otoacoustic Emissions ◽  
Outer Hair Cell ◽  
Cell Damage ◽  
Normal Hearing ◽  
Outer Hair Cells ◽  
Sensory Loss ◽  
Distortion Product ◽  
Hair Cell Damage

Percussionists can be exposed to intermittent sound stimuli that exceed 145 dB SPL, although damage may occur to the outer hair cells at levels of 120 dB SPL. The present study measured distortion-product otoacoustic emissions (DPOAEs) in a group of 86 normal-hearing percussionists and 39 normal-hearing nonpercussionists. Results indicate that normal-hearing percussionists have lower DPOAE amplitudes than normal-hearing nonpercussionists. DPOAE amplitudes were significantly lower at 6000 Hz in both the left and right ears for percussionists. Percussionists also more frequently had absent DPOAEs, with the greatest differences occurring at 6000 Hz (absent DPOAEs in 25% of percussionists vs 10% of nonpercussionists). When all frequencies are considered as a group, 33% of the percussionists had an absent DPOAE in either ear at some frequency, compared to only 23% of the nonpercussionists. Otoacoustic emissions are more sensitive to outer hair cell damage than pure-tone threshold measurements and can serve as an important measurement of sensory loss (i.e., outer hair cell damage) in musicians before the person perceives the hearing loss. DPOAE monitoring for musicians, along with appropriate education and intervention, might help prevent or minimize music-induced hearing loss.

scholarly journals Predicting hearing loss from otoacoustic emissions using an artificial neural network

2002 ◽  
Vol 49 (1) ◽  
Author(s):  
Rouviere De Waal ◽  
René Hugo ◽  
Maggi Soer ◽  
Johann J. Krüger
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Otoacoustic Emissions ◽  
Back Propagation ◽  
Normal Hearing ◽  
Hearing Impaired ◽  
Distortion Product ◽  
Hearing Ability ◽  
Artificial Neural ◽  
Artificial Neural Network Ann

Normal and impaired pure tone thresholds (PTTs) were predicted from distortion product otoacoustic emissions (DP using a feed-forward artificial neural network (ANN) with a back-propagation training algorithm. The ANN used a present and absent DPOAEs from eight DP grams, (2fl -f2 = 406 - 4031 Hz) to predict PTTs at 0.5, 1, 2 and 4 kHz. With normal hearing as < 25 dB HL, prediction accuracy of normal hearing was 94% at 500, 88% at 1000, 88% at 2000 and 93% at 4000 Hz. Prediction of hearing-impaired categories was less accurate, due to insufficient data for the ANN to train on. This research indicates the possibility of accurately predicting hearing ability within 10 dB in normal hearing individuals and in hearing-impaired listeners with DPOAEs and ANNsfrom 500 - 4000 Hz.

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