High Hearing Loss Research Articles

High-frequency hearing loss, occupational noise exposure and hypertension: a cross-sectional study in male workers

BackgroundThe association between occupational noise exposure and hypertension is inconsistent because of an exposure bias caused by outer-ear measurements of noise levels among workers. This study used hearing loss values (HLVs) measured at 4 kHz and 6 kHz in both ears as a biomarker to investigate the chronic effects of noise exposure on hypertension in 790 aircraft-manufacturing workers.MethodsParticipants were divided into a high hearing loss (HL) group (n = 214; average HLVs ≥ 30 decibel [dB] at 4 kHz or 6 kHz bilaterally; 83.1 ± 4.9 A-weighted decibel [dBA]), a median HL group (n = 302; 15 ≤ average HLVs < 30 dB at 4 kHz or 6 kHz bilaterally; 83.1 ± 4.4 dBA) and a low HL group (n = 274; average HLVs < 15 dB at 4 kHz or 6 kHz bilaterally; 82.2 ± 5.1 dBA) based on the results of pure tone audiometry. Multivariate logistic regressions were used to estimate the risk of hypertension between groups.ResultsThe prevalence rates of hypertension were significantly higher in the high HL (43.5%; p = 0.021) and median HL (42.1%; p = 0.029) groups than in the low HL group (33.2%). The high HL and median HL workers had 1.48-fold (95% confidence interval [95%CI] = 1.02-2.15; p = 0.040) and 1.46-fold (95%CI = 1.03-2.05; p = 0.031) higher risks of hypertension relative to the low HL workers. Employment duration was significantly and positively correlated with the risk of hypertension among workers with average HLVs ≥ 15 dB at 4 kHz (p < 0.001) and 6 kHz (p < 0.001) bilaterally.ConclusionsOur findings suggest that high-frequency hearing loss is a good biomarker of occupational noise exposure and that noise-induced hearing loss may be associated with the risk of hypertension.

Detection of Hearing Loss in Audiological Frequencies from Transient Evoked Otoacoustic Emissions

Transient evoked otoacoustic emissions (TEOAEs) have been analyzed for objective assessment of hearing function and monitoring of the influence of noise exposure and ototoxic drugs. This paper presents a novel application of the Hilbert-Huang transform (HHT) for detection and time-frequency mapping of TEOAEs. Since the HHT does not distinguish between signal and noise, it is combined with ensemble correlation in order to extract signal information in intervals with correlated activity. High resolution time-frequency mapping could predict 30 dB HL, or higher hearing loss, at different audiological frequencies in 63-90% of the cases and normal hearing in 75-90% of the cases. The proposed method offers TEOAE time-frequency mapping by constraining the analysis to regions with high signal-to-noise ratios. The results suggest that the HHT is suitable for hearing loss detection at individual frequencies and characterization of the fine structures of TEOAEs.

Prevalence of Hearing Loss and Differences by Demographic Characteristics Among US Adults&lt;subtitle&gt;Data From the National Health and Nutrition Examination Survey, 1999-2004&lt;/subtitle&gt;

Hearing loss affects health and quality of life. The prevalence of hearing loss may be growing because of an aging population and increasing noise exposure. However, accurate national estimates of hearing loss prevalence based on recent objective criteria are lacking. We determined hearing loss prevalence among US adults and evaluated differences by demographic characteristics and known risk factors for hearing loss (smoking, noise exposure, and cardiovascular risks). A national cross-sectional survey with audiometric testing was performed. Participants were 5742 US adults aged 20 to 69 years who participated in the audiometric component of the National Health and Nutrition Examination Survey 1999-2004. The main outcome measure was 25-dB or higher hearing loss at speech frequencies (0.5, 1, 2, and 4 kHz) and at high frequencies (3, 4, and 6 kHz). In 2003-2004, 16.1% of US adults (29 million Americans) had speech-frequency hearing loss. In the youngest age group (20-29 years), 8.5% exhibited hearing loss, and the prevalence seems to be growing among this age group. Odds of hearing loss were 5.5-fold higher in men vs women and 70% lower in black subjects vs white subjects. Increases in hearing loss prevalence occurred earlier among participants with smoking, noise exposure, and cardiovascular risks. Hearing loss is more prevalent among US adults than previously reported. The prevalence of US hearing loss differs across racial/ethnic groups, and our data demonstrate associations with risk factors identified in prior smaller-cohort studies. Our findings also suggest that hearing loss prevention (through modifiable risk factor reduction) and screening should begin in young adulthood.

An assessment of the effect of sound produced in a dental clinic on the hearing of dentists

To assess the effect of sound produced in a dental clinic on the hearing of dentists in a dental school. Thirty-two dentists were evaluated for changes in their hearing thresholds at the Speech and Audiology Department, Manipal College of Allied Health Sciences, Manipal, India. Middle Ear Analyser (MEA), Pure Tone Audiometry (PTA) and Oto-Acoustic Emission (OAE) were used to evaluate changes in the hearing thresholds. There was a change in distortion product (DP) amplitude (temporary shift) in all frequencies. Statistically significant changes were found in the 6 kHz and 4 kHz ranges in the left ear and 6 kHz in the right ear. There was a larger DP shift in the left ear than in the right ear. A comparison of the hearing thresholds of males and females showed a significant difference of 3 kHz in the left ear, where males had a higher hearing loss. There were shifts of hearing threshold at 6 kHz and 4 kHz. The danger to hearing from dental clinic working environment in a dental school cannot be underestimated.

EOAE I/O curves in inner ear impairments

Input/output (I/O) curves of evoked otoacoustic emissions (EOAEs) reveal a saturation at 30 dB or thereabout above their detection threshold. It has been suggested that such I/O relation corresponds to that of the basilar membrane vibration related with an active electro-mechanical process of outer hair cells. EOAEs in response to 1–2 kHz short tone bursts were measured. EOAEs were examined in ears with idiopathic sudden hearing loss (HL), low tone type acute sensorineural HL, Ménière's disease and noise-induced HL. Three types of shift that were downward, horizontal and combined were observed in their I/O curves. The downward shift was seen mainly in the ears with high tone HL and the horizontal shift was in the ears with low tone HL. Three types of shift were observed in the ears of Ménière's disease, in which glycerol administration augmented EOAE amplitude beyond the normal saturation level of its cotralateral side. Measurements of EOAE I/O curves are useful for diagnosis of inner ear impairments related to outer hair cell dysfunction in ears with sensorineural HL.