Distortion Product Otoacoustic Emissions In Ears Research Articles

Association of age, gender and duration of diabetes with distortion product otoacoustic emissions in type 2 diabetes mellitus

Introduction: Screening of outer hair cells is necessary in identification of undetected hearing loss. Objectives: Present study is focused on functional analysis of outer hair cells by distortion product otoacoustic emissions (DPOAEs) in type 2 diabetes with and without hearing impairment. Materials and Methods: This is a cross-sectional study, two groups i.e. WoHI (n=50) and WHI (n=50) of either sex with an age group of 35-55 were included. DPOAE screening is a non-invasive test protocol that assists to detect the accuracy of cochlear outer hair cell functioning and hearing at frequencies ranging from 1000Hz-4000Hz. Statistical Analysis: The data were analyzed by Chi-square test to see the association between DPOAE screening of both the ears in WoHI and WHI groups with age, gender, duration of diabetes. Results: The association of age with DPOAEs in WoHI and WHI groups, fail percentage of the right ear DPOAE in the age group 35-44 years were 11.5% and 16.6% respectively, it was not statistically significant (P=0.891). The association of gender with DPOAE screening in WoHI and WHI groups, fail percentage of the right ear DPOAE in the male group were 12% and 15% respectively and in the female group were 6.3% and 20% respectively, it was not statistically significant (P=0.435). Conclusion: OAE alone does not assess the entire auditory pathway in diabetic persons. A thorough case history including duration of disease, age of onset and frequency of HbA1C monitoring and OAE screening is a quick noninvasive clinically feasible procedure for potentially identifying or detecting hearing impairment. Keywords: Type 2 diabetes, DPOAEs, Duration of diabetes, WHI, WoHI.

Effect of mastoid drilling on the distortion product otoacoustic emissions in the non operated ear

ObjectiveTo monitor the effect of mastoid drilling on the non-operated ear distortion product otoacoustic emissions. Materials and methodsDistortion product otoacoustic emissions (DPOAEs) were measured at frequencies of f 2=2, 3, 4 and 5kHz, and a frequency ratio f 1 /f 2=1.22. DPOAEs were measured in 49 cases, pre and post-operatively who underwent mastoid drilling procedures, compared with each other and with 49 controls who underwent myringoplasty and myringotomy procedures. ResultsAmplitudes of DPOAEs decreased significantly in those who underwent mastoidectomies over all the measured frequencies in the immediate post-operative period but had recovered by the seventh post operative day. ConclusionDrill induced noise can cause temporary decrease in the DPOAEs postoperatively and hence temporary hearing loss for a period of one week.

Effects of Negative Middle Ear Pressure on Distortion Product Otoacoustic Emissions and Application of a Compensation Procedure in Humans

This study was intended to systematically examine the effect of negative middle ear pressure (MEP) on distortion product otoacoustic emissions (DPOAEs) and to validate a compensation procedure to account for negative MEP encountered in DPOAE measurement. In experiment 1, the 2f1 - f2 DPOAE was measured for nine f2 frequencies from 600 to 8000 Hz in 16 adults under three MEP conditions: normal MEP, negative MEP, and compensated MEP. The subjects' voluntarily induced negative MEPs, with magnitudes ranging from -40 to -420 daPa, were measured tympanometrically with the tympanometric peak pressure. Each negative MEP was then compensated for by applying an equivalent amount of negative air pressure into the ear canal. The three MEP conditions were compared in terms of difference in DPOAE level. Experiment 2 was conducted to measure the DPOAE under normal and negative MEP conditions by using a different system with a higher frequency resolution in 19 subjects. Negative MEP generally attenuated DPOAEs more for low frequencies than for high frequencies. For the frequencies of 1000 Hz and below, the mean DPOAE level was reduced by at least 4 to 6 dB for negative MEPs lower than -100 daPa (i.e., less negative). Reduction of the DPOAE level increased with increasing negative MEP (e.g., 10 to 12 dB for -160 daPa and higher, i.e., more negative). For f2 = 2000, 4000, and 6000 Hz, the effect of negative MEP was not significant. For 3000 Hz, DPOAE-level reduction was significant (e.g., 5 dB for MEP = -70 to -95 daPa and up to 12 dB for -290 to -420 daPa). As a result, a peak at 2000 Hz and a notch at 3000 Hz appeared in the DPOAE change versus frequency function. For 8000 Hz, DPOAE levels tended to increase in high negative MEPs, although the changes were not significant. Intersubject variability in the effect of negative MEP on DPOAEs was large. As the negative MEPs were compensated for, the decreased DPOAE levels were significantly corrected. DPOAEs measured with higher resolution in experiment 2 verified the frequency-specific effects of negative MEPs. Results revealed that the peak and notch in the DPOAE change versus frequency function shifted toward higher frequencies when negative MEP was increased, and a second peak emerged at a higher frequency. Negative MEP substantially decreases DPOAE level for low frequencies and some mid-frequencies but tends to increase DPOAE level for high frequencies. Results suggest that any degree of negative MEP should be corrected to obtain an accurate outcome of DPOAE measurement. The MEP compensation procedure is effective in restoring normal DPOAEs in ears with negative MEPs. Examining changes in DPOAE level under negative MEP allows for further study of the transmission of acoustic signals through an altered middle ear system. A minimal change of DPOAE level at 2000 Hz indicates that the primary resonant frequency of the middle ear is lower than 2000 Hz. The variation in DPOAE change in the middle to high frequency range implies multiple resonances of the middle ear system.

Influence of spontaneous otoacoustic emissions on distortion product otoacoustic emission amplitudes

Although the influence of the levels and ratios of the primary stimulus on the amplitude of distortion product otoacoustic emissions (DPOAEs) has been studied intensely, the influence of the presence of spontaneous otoacoustic emissions (SOAEs) has been investigated less thoroughly. The present investigation analysed whether the unilateral presence of 58 SOAEs in 43 normal-hearing adults was related to larger DPOAEs in the ear with SOAEs compared to the contralateral ear having no SOAEs. The study was designed such that the only factor that could influence the amplitude of DPOAEs was the presence of SOAEs. Input/output ( I/ O) functions were collected in response to primary tones that were presented in 5-dB steps from 70 to 40 dB SPL at the frequency of the unilaterally recorded SOAE of each subject. The primary outcome was the demonstration of statistically significant ( P<0.05) larger DPOAEs in ears exhibiting SOAEs than in ears without measurable SOAEs, except at the highest stimulus level of 70 dB SPL. These results suggest that SOAEs play an additive role in the measurement of DPOAEs. The enhancing effect of the unilateral presence of SOAEs on DPOAEs was statistically significant for 65 dB SPL and lower levels of primary tones. The authors speculate that passive cochlear properties begin to participate in the generation of DPOAEs at primary-stimulus levels greater than 65 dB SPL.

Distortion-Product Otoacoustic Emissions (DPEs) in Neonates: Frequency Ratio (F2/F1) and Stimulus Level Differences (L1-L2)

Stimulus parameter values for distortion-product otoacoustic emissions (DPE) recordings in neonates are based on adult studies. The purpose of the present investigation was to determine what values of stimulus frequency ratio (F2/F1) and stimulus level difference (L1-L2) produced the largest DPE amplitude in neonates. Single ear DPE measurements were obtained from 11 preterm neonates (34-36 weeks post-conceptual age) at F2s of 2, 3, and 4 kHz. Ratio sweeps were performed through a frequency range determined by F2/F1=1.4-1.02 at L1-L2s of 0, 5, 10, 15 and 20 dB, where L1=65 dB SPL. The findings indicated that on average, an L1-L2=5 dB and an F2/F1=1.18 produced the largest DPE amplitude across all F2s.

On the existence of an age/threshold/frequency interaction in distortion product otoacoustic emissions.

Interactions among age, threshold, and frequency in relation to distortion product otoacoustic emissions (DPOAE) have yet to be resolved. The effects of these variables were explored by analyzing DPOAEs in ears with thresholds not exceeding 20 dB HL. Multivariate regression analyses were performed in two different ways. For data to be included in the first analysis, audiometric threshold had to be 20 dB HL or better only at the particular frequency under study, but might exceed 20 dB HL at other half-octave frequencies. Significant main effects were found for age, threshold, and frequency. There was also an age-by-frequency interaction, but a significant age-by-threshold interaction was not observed. DPOAE amplitudes decreased as either age, frequency, or threshold increased. In the second analysis, when a more stringent inclusion criterion was applied (normal thresholds at all frequencies), the main effects for age, threshold, and frequency were not significant. The significant age-by-frequency interaction remained, whereby DPOAE amplitudes decreased as age and frequency increased, but the age-by-threshold interaction again was not significant. The magnitude of DPOAE amplitude change across age, threshold, and frequency and for the age-by-frequency interaction was small but similar for both groups of subjects. Age in association with threshold did not account for observed changes in DPOAE amplitudes for either group. Importantly, the lack of a significant age-by-threshold interaction indicates that there may be processes intrinsic to aging alone that act on DPOAE generation.