Average Hearing Threshold Level Research Articles

Trends in Distributions of Hearing Threshold Levels by Ages: A Comparison of the ISO 7029 and Newly Available Country-Specific Data.

Hearing thresholds provide essential information and references about the human auditory system. This study aimed to identify changing trends in distributions of hearing threshold levels across ages by comparing the International Organization for Standardization (ISO) 7029 and newly available data after publishing ISO 7029. To compare ISO 7029 and newly available hearing threshold data after publishing ISO 7029, four country-specific datasets that presented average hearing threshold levels under conditions similar to ISO 7029 were utilized. For frequencies between 125 Hz and 8,000 Hz, the deviations of hearing threshold values by ages from the hearing threshold of the youngest age group for each data point were utilized. For frequencies from 9,000 Hz to 12,500 Hz, the median threshold information was utilized. Hearing threshold data reported after publishing ISO 7029 from the four countries were mostly similar to the ISO 7029 data but tended to deviate in some age groups and sexes. As national hearing threshold trends change, the following ISO 7029 revision suggests the need to integrate hearing threshold data from different countries.

Objective multidisciplinary measurements of sleep disturbance and autonomic dysfunction as risk factors for chronic subjective tinnitus

This observational study assessed sleep disturbance and autonomic dysfunction as risk factors for chronic subjective tinnitus through polysomnography (PSG) and autonomic function tests. Adult patients with chronic subjective tinnitus who visited the department of otolaryngology in our hospitals (n=40), along with controls without tinnitus (n=80), were recruited. Individuals with an average hearing threshold level (HL) exceeding 25dB HL and a known diagnosis of insomnia were excluded. Objective assessments comprised pure-tone audiometry, PSG, and autonomic function tests (e.g., the cold pressor test). Patients with prolonged sleep latency, lower sleep efficiency, and sympathetic hyperactivity had significantly higher risks of developing tinnitus. No interaction effect between poor sleep quality and sympathetic hyperactivity on tinnitus was detected. This is the first study to administer PSG and autonomic function tests to patients with chronic subjective tinnitus. Poor sleep quality and autonomic dysfunction were implicated as risk factors for tinnitus. PSG and the autonomic function tests helped identify tinnitus-related comorbidities and inform tinnitus treatment. Sleep disturbance and autonomic dysfunction did not exert an interaction effect on tinnitus. Further studies with a larger sample size and the inclusion of patients with more severe tinnitus are warranted.

Influence of Gender on Auditory Temporal Processing: A Cross-sectional study in Security Personnel in Puducherry, India

ABSTRACT Introduction: It is no wonder that men and women have their fair share of differences. Scientific evidences are scarce to justify the clear-cut role of gender differences on the human brain. It is a well-known fact that perception and accurate processing of sound stimuli in the auditory pathway is a necessary skill for efficient learning and language development. This study aimed to investigate the role of gender on auditory processing by comparing the temporal resolution ability of healthy, adult males and females. Methods: Forty-three apparently healthy individuals (F = 18; M = 25) in the age group of 25–60 years with a normal hearing threshold on audiometry participated in this study. Audiometry and random gap detection test (RGDT) were used to assess hearing threshold and auditory temporal processing ability. In RGDT, a pair of pure tones was presented to participants’ ears at different frequencies (500–4000 Hz) and they were instructed to identify a silent-gap (in milliseconds) between each pair of tones. Values were compared using an unpaired student “t” test. Results: The mean age of participants was 40.5 ± 8.45 years. The average hearing threshold levels (in dB) of male and female participants were 15.6 ± 2.5 and 14.5 ± 2.8, respectively (P-value = 0.1293). Temporal processing values of males and females were 10.48 ± 0.49 and 10.67 ± 0.51, respectively (P-value = 0.2338). Conclusion: The temporal processing ability was slightly higher in males than the females. However, the difference was insignificant. Therefore, it can be concluded that gender does not affect auditory temporal processing ability in middle-aged adults.

Occupational Hearing Loss Associated With Non-Gaussian Noise: A Systematic Review and Meta-analysis.

Epidemiological characteristics of occupational noise-induced hearing loss (NIHL) associated with non-Gaussian noise are still unclear and have been rarely reported in the literature. The relationships between non-Gaussian noise exposure and occupational NIHL were analyzed based on the published papers. Systematic review and meta-analysis of epidemiological studies were performed. Of 78 epidemiological studies (47,814 workers) selected, there were seven cohort studies and 71 cross-sectional studies. The incidence of high-frequency NIHL (HFNIHL) and speech-frequency NIHL (SFNIHL) in the seven cohort studies was 10.9 and 2.9%, respectively. In 71 cross-sectional studies, the prevalence of HFNIHL and SFNIHL was 34.2 and 18.9%, respectively. The average hearing threshold level at the high frequencies was 42.1 ± 17.4 dB HL. Workers exposed to non-Gaussian noise had a higher risk of developing HFNIHL than those not exposed to noise (overall-weighted odds ratio [OR] = 4.46) or those exposed to Gaussian noise (overall-weighted OR = 2.20). The Chi-square trend test demonstrated that the prevalence of HFNIHL was positively correlated with age, cumulative noise exposure, and exposure duration (p < 0.001). Workers exposed to non-Gaussian noise suffered from greater NIHL than those exposed to Gaussian noise or not exposed to noise. Age, exposure duration, noise level, and noise temporal structure were the main risk factors for occupational NIHL. The A-weighted equivalent continuous sound pressure level (LAeq) is not a sufficient measurement metric for quantifying non-Gaussian noise exposure, and a combination of kurtosis and noise energy metrics (e.g., LAeq) should be used. It is necessary to reduce the exposure of non-Gaussian noise to protect the hearing health of workers.

Effects of Vibrant Soundbridge on tinnitus accompanied by sensorineural hearing loss.

Tinnitus is a common symptom among patients with hearing loss, and many studies have reported successful tinnitus suppression with hearing devices. Active middle ear implantation of the Vibrant Soundbridge (VSB) is a good alternative to existing hearing devices. This study evaluated the effects of VSB implantation on tinnitus and sought to identify the main audiological factor that affects tinnitus suppression. The study participants were 16 adults who had tinnitus with sensorineural hearing loss, and who underwent VSB implantations. Pure-tone audiometry; word recognition test; tinnitus handicap inventory (THI); and visual analog scale (VAS) assessment of loudness, awareness, and annoyance were performed before and 12 months after surgery. Changes in hearing threshold, word recognition scores (WRS), THI scores, and VAS scores were analyzed. VAS scores for loudness (mean difference: 1.9, 95% CI: 0.6, 3.1), awareness (mean difference: 1.6, 95% CI: 0.4, 2.8), and annoyance (mean difference: 1.7, 95% CI: 0.7, 2.8) showed significant improvements from baseline to 12 months after surgery. In addition, THI scores showed a significant decrease (mean difference: 13.8, 95% CI: 2.9, 24.9). The average hearing threshold level, WRS, and most comfortable level (MCL) also showed significant improvements at 12 months after surgery (mean difference: 17.3, 95% CI: 13.3, 21.3; mean difference: -7.6, 95% CI: -15.1, -0.1; mean difference: 26.3, 95% CI: 22.9, 29.6, respectively). Among the aforementioned factors, changes in MCL were best correlated with those in THI scores (mean difference: 2.55, 95% CI: 0.90, 4.21). A VSB implant is beneficial to subjects with tinnitus accompanied by sensorineural hearing loss. The changes in THI scores best correlated with those in MCL. This improvement may represent a masking effect that contributes to tinnitus suppression in patients with VSB implants.

Comparison of frequency-Specific hearing thresholds between pure-tone audiometry and auditory steady-state response

Introduction: Hearing assessment in difficult to assess persons gives inconsistent response in free field hearing and pure-tone audiometry (PTA). We have been performing brainstem evoked response audiometry (BERA) as an objective assessment in such cases. BERA has limitations that it is not frequency specific, measures thresholds in higher frequencies only, signal intensity levels cannot be higher than 90 dB and presents the data in waveform which needs to be interpreted by experienced audiologist to deduce correct information. All these limitations can be negated with use of auditory steady-state response (ASSR) which can present intensity levels till 120 dB, is frequency specific, even for lower frequencies and has automated response and deduction analysis. The aim of our study was to compare pure-tone thresholds with ASSR thresholds in normal hearing and hearing loss subjects with an objective to validate the ASSR as a tool for objective hearing assessment. Materials and Methods: In this prospective cross-sectional study of 70 adults (n = 140 ears) of both genders, with and without hearing complaints, Group 1 consisted of 24 individuals of normal hearing, Group 2 consisted of 25 individuals of sensorineural hearing loss, and 21 individuals with conductive hearing loss in Group 3. The patients were evaluated with PTA and ASSR test. The mean pure tone and ASSR thresholds for each frequency were calculated and analyzed using the SPSS IBM software. Results: The mean difference of ASSR with PTA was noted at 9.92 dB in the right ear and 10 dB in the left ear. A high significant correlation was noted between ASSR and PTA with P(0.0005) across all the three groups. The relationship between the PTA and ASSR measurement for measuring average hearing threshold levels is described by the equation: PTA = ASSR mean × 0.99–9.92. Conclusion: ASSR is an excellent tool to predict accurate level of frequency-specific hearing threshold. It has constant relationship with pure tone thresholds. ASSR can predict true hearing thresholds in “difficult to assess” patients such as children and malingerers. This can also be used in the prediction of disability assessment objectively.

Hearing loss before and after cisplatin-based chemotherapy in testicular cancer survivors: a longitudinal study

Background: Hearing loss is a well-known long-term effect after cisplatin-based chemotherapy (CBCT) in testicular cancer survivors (TCS), but longitudinal data are sparse. We evaluate hearing loss and the impact of age in TCS treated with CBCT in this longitudinal study.Material and methods: Forty-six TCS treated with CBCT 1980–1994 with audiograms (0.25–8 kHz) pre-chemotherapy (PRE) and at a follow-up survey (SURV) after median 10 years were included (cases). Audiograms at SURV from 46 age-matched TCS without CBCT were included as controls. Linear regression was performed to evaluate predictors for change in the hearing threshold level (HTL) from PRE to SURV. Two definitions of a audiogram-defined hearing loss was applied if: (1) mean HTL for both ears exceeded 20 dB at any frequency 0.25–8 kHz (American Speech-Language-Hearing Association (ASHA) definition) and (2) average HTL for the frequencies 0.5, 1, 2 and 4 kHz exceeded 20 dB (WHO-M4 definition). Self-reported hearing impairment (SURV) was assessed by a questionnaire.Results: Age and cisplatin dose was significantly associated with a greater change in HTL for the frequencies 2–8 kHz. For the 8 kHz frequency, each 100 mg increase in cumulative cisplatin dose was associated with a deterioration of 3.6 dB (95% CI 1.8–5.3, p < .001). The prevalence of hearing loss (ASHA) among cases was 33% PRE, 70% at SURV and 65% among controls at SURV (cases vs. controls, p = .66). According to M4, the prevalence of hearing loss among cases was 6.5% PRE, 13% at SURV and 2.2% among controls at SURV (cases vs. controls, p = .049). Twenty-nine percent of cases, and 33% of controls (p = .70) reported hearing impairment at SURV.Conclusion: Cisplatin is associated with a hearing loss particularly at higher frequencies. Age appear to be an important factor for hearing loss regardless of treatment. The ASHA definition overestimates the hearing problem.

International Outcome Inventory for Hearing Aids: Data From a Large Swedish Quality Register Database.

The purpose of this study was to analyze a database of completed International Outcome Inventory for Hearing Aids (IOI-HA) questionnaires obtained from over 100,000 clients fitted with new hearing aids in Sweden during the period of 2012-2016. Mean IOI-HA total scores were correlated with degree of hearing loss, unilateral versus bilateral fitting, first-time versus return clients, gender, and variation among dispensing clinics. The correlations with expectations, service quality, and technical functioning of the hearing aids were also analyzed. Questionnaires containing the 7 IOI-HA items as well as questions concerning some additional issues were mailed to clients 3-6 months after fitting of new hearing aids. The questionnaires were returned to and analyzed by an independent research institute. More than 100 dispensing clinics nationwide take part in this project. A response rate of 52.6% resulted in 106,631 data sets after excluding incomplete questionnaires. Forty-six percent of the responders were women, and 54% were men. The largest difference in mean score (0.66) was found for the IOI-HA item "use" between return clients and first-time users. Women reported significantly higher (better) scores for the item "impact on others" compared with men. The bilaterally fitted subgroup reported significantly higher scores for all 7 items compared with the unilaterally fitted subgroup. Experienced users produced higher scores on benefit and satisfaction items, whereas first-time users gave higher scores for residual problems. No correlation was found between mean IOI-HA total score and average hearing threshold level (pure-tone average [PTA]). Mean IOI-HA total scores were found to correlate significantly with perceived service quality of the dispensing center and with the technical functionality of the hearing aids. When comparing mean IOI-HA total scores from different studies or between groups, differences with regard to hearing aid experience, gender, and unilateral versus bilateral fitting have to be considered. No correlation was found between mean IOI-HA total score and degree of hearing loss in terms of PTA. Thus, PTA is not a reliable predictor of benefit and satisfaction of hearing aid provision as represented by the IOI-HA items. Identification of a specific lower fence in PTA for hearing aid candidacy is therefore to be avoided. Large differences were found in mean IOI-HA total scores related to different dispensing centers.

Audiograms and hearing loss before and after cisplatin-based chemotherapy (CBCT) in testicular cancer survivors (TCS).

e16047 Background: 80% of TCS were reported to have a hearing loss based on post-CBCT audiograms (American Speech-Language-Hearing Association (ASHA) definition; Frisina et al, JCO 2016:34) Methods: 46 TCS treated with CBCT 1980-1994 with audiograms (0.25-8 kHz) pre chemotherapy (PRE) and at a survey (SURV) after median 10 years were included (cases). Audiograms at SURV from 46 age-matched TCS without CBCT were included as controls. Linear regression was performed to evaluate predictors for change in hearing threshold level (HTL) from PRE to SURV. Mean HTL for both ears exceeding 20 dB at any frequency 0.25-8 kHz were classified as a hearing loss (ASHA definition). We also applied the WHO definition of hearing loss, present if the average HTL threshold for the four frequencies 0.5, 1, 2 and 4 kHz exceeded 20 dB (M4 definition). At SURV, self-reported hearing loss was assessed by a questionnaire (categorized as “a little”, “quite a bit” and “very much” vs. “not at all”). Results: Age and PRE HTL was associated with change in HTL for most frequencies. Cisplatin dose was significantly associated with change in HTL for the frequencies 2 to 8 kHz, with a gradually greater change in HTL and lower p-value with increasing frequencies. For the 8 kHz frequency, each 100 mg increase in cumulative cisplatin dose was associated with a deterioration of 3.6 dB (p &lt; .001). According to ASHA, the prevalence of a hearing loss among cases was 33% PRE, 70% at SURV, and 65% among controls at SURV (cases vs. controls, p = .66). According to M4, the prevalence of hearing loss among cases was 6.5% PRE, 13% at SURV, and 2.2% among controls at SURV (cases vs. controls, p = 0.05). Overall 29% of cases, and 33% of controls (p = .70) reported some degree of hearing impairment at SURV, of whom only 6.5% of cases reported more than “a little”. Self-reported hearing loss was not associated with hearing loss according to ASHA (p = .20), but was associated with the M4 definition (p = .02). Conclusions: Cisplatin is associated with a moderate hearing loss particularly at higher frequencies. Ageing is important for hearing loss regardless of treatment. The ASHA definition of hearing loss overestimates the hearing problem and should not be used as a clinical tool.

The association of obesity with hearing thresholds in women aged 18–40 years

An elevation in hearing thresholds and decrease in hearing sensitivity in adults, particularly due to aging, are quite common. Recent studies have shown that, apart from aging, various other factors also play a role in auditory changes. Studies on the association of hearing loss (HL) with obesity are limited in advanced age cases and present contradictions. In this study, the association between obesity and hearing thresholds in women aged 18-40 years has been assessed. Forty women diagnosed with obesity (mean age, 31.8 years) and 40 healthy non-obese female controls (mean age, 30.5 years) were included in this prospective study. Each subject was tested with low (250, 500, 1000 and 2000 Hz) and high (4000, 6000 and 8000 Hz) frequency audiometry. In the case and control groups, the average hearing thresholds at low frequencies were 16.03 ± 4.72 and 16.15 ± 2.72 (p = 0.885) for the right ear, respectively, and 16.15 ± 5.92 and 14.71 ± 3.18 (p = 0.180) for the left ear, respectively. The average hearing threshold levels at high frequencies were 20.70 ± 10.23 and 15.33 ± 3.87 (p = 0.003), respectively, for the right ear, and 22.91 ± 15.54 and 15.87 ± 4.35 (p = 0.007), respectively, for the left ear with statistical significance. This is the first report on the association of obesity with hearing threshold in women aged 18-40 years. We have demonstrated that obesity may affect hearing function, particularly that related to high frequencies. Hearing loss can be prevented by avoidance or control of obesity and its risk factors. Moreover, an auditory screening of obese cases at an early stage may provide early diagnosis of HL and may also contribute to their awareness in the fight against obesity.

In Vivo Cochlea Hair Cell Rescue after Noise‐Induced Hearing Loss Using Low‐Level Laser Therapy

Objectives: There is no study regarding the effects of low level laser therapy (LLLT) on cochlear after noise-induced hearing loss (NIHL). The aims of this study were to (1) elucidate the ability of LLLT applied to noise-induced damaged cochlea to recover NIHL and (2) demonstrate histopathological changes of remaining outer hair cells (OHCs). Methods: A total of 6 rats (C group) for control and 9 rats (N group) as the noise-exposure group were included. Nine rats were exposed to noise once and the left ears (NL side) were treated with low-level laser daily. Right ears (N side) were the control sides. Hearing thresholds were observed through auditory brainstem response recordings. Thresholds were monitored before noise exposure and also after the twelfth irradiation. Cochlear pathology and number of OHCs were observed by scanning electron microscopy. Results: The initial average hearing threshold levels were 26 ± 4, 24 ± 5, 24 ± 5, 24 ± 3, 24 ± 5 dB SPL in 4, 8, 12, 16, 32 kHz, respectively. After noise exposure, N group thresholds were 63 ± 15, 64 ± 16, 71 ± 11, 73 ± 15, 67 ± 14 dB SPL. After 12 irradiations, NL side thresholds recovered significantly (27 ± 4, 26 ± 4, 28 ± 8, 30 ± 9, 27 ± 6 dB SPL, P &lt; .05). N side thresholds were 46 ± 16, 51 ± 13, 63 ± 16, 50 ± 12, 48 ± 14 dB SPL. OHC number was significantly larger in the NL side than the N side. In the C group, OHCs counts were 176 ± 16, 146 ± 5, 154 ± 6 cells for apical, middle, basal turns, respectively. N side counts were 122 ± 2, 113 ± 2, and 116 ± 19. NL side counts displayed promising results (167 ± 27, 140 ± 29, 129 ± 26). Conclusions: This study demonstrates that LLLT promotes recovery of hearing and OHCs survival from apoptotic changes by NIHL.

Inflammation is associated with a worsening of presbycusis: Evidence from the MRC national study of hearing

Objective: Inflammaging, a state of chronic inflammation in the elderly, is now thought to be a key element of the ageing process and contributor to age-related disease. In a previously published study, we identified a significant association between inflammation levels and severity of presbycusis among individuals aged 63 to 73 (ʽyounger old”) within an available audiometric range 0.5 to 4 kHz. Our aim was to see if this association would be identified among participants in the MRC national study of hearing, and whether the strength of the association would increase with greater age, or for very low or very high audiometric frequencies. Design: Cross-sectional analysis of cohort data. Study sample: Three hundred and sixty community-dwelling adults age 60 years and over, representing all those with white blood cell count and audiometric data available. Results: A significant independent association between (higher) WBC and (worse) hearing level was identified. This effect increased with age. The strongest association was among those over 75, for whom average hearing threshold levels among those with lower WBC was 17 dB better than those with higher WBC. Conclusions: The current findings support an association between inflammaging (a condition potentially amenable to pharmacological treatment or lifestyle management) and presbycusis.

Assessment of the American Medical Association guide to the evaluation of binaural hearing impairment

Objective: To assess the American Medical Association (AMA) guide to the evaluation of binaural hearing impairment (BHI) as a procedure for estimating severity of hearing loss from audiograms. Design: The BHIs of Australian war veterans were calculated from their hearing threshold levels (HTLs) and compared with their scores on a hearing questionnaire, the hearing measurement scale (HMS). Study sample: The HTLs of 282 Australian war veterans were measured at frequencies from 0.25 to 8 kHz and scores on the HMS were obtained from 154 of those veterans. Results: No grounds could be found for altering the frequencies included in the average HTL or the high fence of 92 dB HL used in calculating the monaural hearing impairments (MHIs) of the veterans, and no grounds could be found for altering the ratio of 5:1 used in determining the BHI from the MHIs of the better and worse ears. However, agreement between HMS score and BHI was improved by reducing the low fence used in calculating MHI from 25 to 15 dB HL. Conclusion: A modified version of BHI provided an improved procedure for estimating severity of hearing loss from audiograms but would not be suitable for compensation purposes.

Markers of inflammatory status are associated with hearing threshold in older people: findings from the Hertfordshire ageing study

Age-related hearing loss is a common disabling condition but its causes are not well understood and the role of inflammation as an influencing factor has received little consideration in the literature. To investigate the association between inflammatory markers and hearing in community-dwelling older men and women. Cross-sectional analysis within a cohort study. The Hertfordshire Ageing Study. A total of 343 men and 268 women aged 63-74 years on whom data on audiometric testing, inflammatory markers and covariates were available at follow-up in 1995. Average hearing threshold level (across 500-4,000 Hz) of the worst hearing ear and audiometric slope in dB/octave from 500 to 4,000 Hz. Older age, smoking, history of noise exposure and male gender (all P < 0.001) were associated with higher mean hearing threshold in the worse ear in univariate analysis. After adjustment for these factors in multiple regression models, four measures of immune or inflammatory status were significantly associated with hearing threshold, namely white blood cell count (r = 0.13, P = 0.001), neutrophil count (r = 0.13, P = 0.002), IL-6 (r = 0.10, P = 0.05) and C-reactive protein (r = 0.11, P = 0.01). None of the inflammatory markers was associated with maximum audiometric slope in adjusted analyses. Markers of inflammatory status were significantly associated with degree of hearing loss in older people. The findings are consistent with the possibility that inflammatory changes occurring with ageing may be involved in age-related hearing loss. Longitudinal data would enable this hypothesis to be explored further.

The Ala54Thr polymorphism in the fatty acid-binding protein 2 (FABP2) gene is associated with hearing impairment: A preliminary report

Objective The fatty acid-binding protein 2 (FABP2) is involved in the transport and metabolism of fatty acids. The FABP2 gene has been proposed as a candidate gene for diabetes and obesity. This study evaluates the hearing impairment risk in the Ala54Thr polymorphism of FABP2 in middle-aged and elderly Japanese. Methods Our sample population comprised 1428 community-dwelling Japanese aged 40–86 years (mean ± standard deviation [SD]: 63.1 ± 9.8) who participated in the Study of Aging between 2004 and 2006. An average hearing threshold level greater than 25 dB in the better ear for frequencies 500, 1000, 2000 and 4000 Hz was defined as hearing impairment. Data were analyzed by means of a multiple logistic regression with adjustment for potential confounders. Results The per-allele odds ratio for hearing impairment risk was 1.262 (95% confidence interval [CI]: 1.012–1.574) in model 1, adjusting for age, sex, history of ear disease, and history of occupational noise exposure; and 1.259 (CI: 1.009–1.571) in model 2, which adjusted for diabetes, body mass index and the histories of heart disease and hypertension, as well as the moderators in model 1. A significant adverse effect of the Thr54 variant on hearing was observed and the effect was independent of both diabetes and obesity in the present analyses. Conclusions This study demonstrated that the Ala54Thr polymorphism of FABP2 was associated with a risk of hearing impairment in middle-aged and elderly people. The results might support caloric restriction theory indirectly, but additional researches are desired.

Endothelin‐1 gene polymorphism and hearing impairment in elderly Japanese

To investigate the association between the Lys198Asn (G/T) polymorphism (rs5370) in the endothelin-1 gene (EDN1) and hearing impairment in middle-aged and elderly Japanese. Longitudinal study. Data were collected from community-dwelling Japanese adults who participated in the Longitudinal Study of Aging biennially between 1997 and 2006. The participants at baseline were 2,231 adults aged 40 years to 79 years. An average hearing threshold level of 25 dB or better in the better ear for frequencies 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz was defined as no hearing impairment. Using generalized estimating equations to treat repeated observations within subjects, 7,097 cumulative data were analyzed to assess the association between hearing status and the EDN1 G/T polymorphism with adjustment for age, sex, histories of ear disease, occupational noise exposure, heart disease, hypertension, and body mass index under additive, dominant, and recessive genetic models. Comparison with wild-type homozygotes (GG), heterozygotes, and mutant homozygotes (GT/TT) showed a positive association with hearing impairment after adjustment for age in model 1 (odds ratio [OR] = 1.24; 95% confidence interval [CI] = 1.02-1.50; P = .033), for age and sex in model 2 (OR = 1.29; CI = 1.06-1.57; P = .0122), and for age, sex, history of ear disease, and history of occupational noise exposure in model 3 (OR = 1.31; CI = 1.07-1.60; P = .0092). The association was also significant in model 3 under the additive model. This study demonstrated that mutant T-allele carriers were associated with a higher risk of hearing impairment than carriers of wild-type homozygotes in middle-aged and elderly people. This result implies that endothelin-1 plays a valuable role in the cochlea.

Multiple work-related accidents: tracing the role of hearing status and noise exposure

Objectives:Our main purpose was to investigate any relationship between noise exposure levels in the workplace, degree of hearing loss (HL), and the relative risk of accident (OR of single or...

Could Driving Safety be Compromised by Noise Exposure at Work and Noise-Induced Hearing Loss?

Objective. A study was conducted to verify if there is an association between occupational noise exposure, noise-induced hearing loss and driving safety expanding on previous findings by Picard, et al. (2008) that the two factors did increase accident risk in the workplace. Methods. This study was made possible when driving records of all Quebec drivers were made available by the Société de l'assurance automobile du Québec (SAAQ is the state monopoly responsible for the provision of motor vehicle insurance and the compensation of victims of traffic accidents). These records were linked with personal records maintained by the Quebec National Institute of Public Health as part of its mission to prevent noise induced hearing loss in the workplace. Individualized information on occupational noise exposure and hearing sensitivity was available for 46,030 male workers employed in noisy industries who also held a valid driver's permit. The observation period is of five years duration, starting with the most recent audiometric examination. The associations between occupational noise exposure levels, hearing status, and personal driving record were examined by log-binomial regression on data adjusted for age and duration of exposure. Daily noise exposures and bilateral average hearing threshold levels at 3, 4, and 6 kHz were used as independent variables while the dependent variables were 1) the number of motor vehicle accidents experienced by participants during the study period and 2) participants' records of registered traffic violations of the highway safety code. The findings are reported as prevalence ratios (PRs) with their 95% confidence intervals (CIs). Attributable numbers of events were computed with the relevant PRs, lesser-noise, exposed workers and those with normal hearing levels making the group of reference. Results. Adjusting for age confirmed that experienced workers had fewer traffic accidents. The data show that occupational noise exposure and hearing loss have the same effect on driving safety record than that reported on the risk of accident in noisy industrial settings. Specifically, the risk of traffic accident (PR = 1.07 (CI 95% [1.01; 1.15]) is significantly associated with the daily occupational noise exposures ≥ 100 dBA. For participants having a bilateral average hearing loss ranging from 16 to 30 dB, the PR of traffic accident is 1.06 (CI 95% [1.01; 1.11]) and reaches 1.31 (CI 95% [1.2; 1.42]) when the hearing loss exceeds of 50 dB. A reduction in the number of speeding violations occurred among workers occupationally exposed to noise levels ≥ 90 dBA and those with noise-induced hearing loss ≥16 dB. By contrast, the same individuals had an increase in other violations of the Highway safety code. This suggests that noise-exposed workers might be less vigilant to other traffic hazards. Conclusion. Daily occupational noise exposures ≥ 100 dBA and noise-induced hearing losses—even when just barely noticeable—may interfere with the safe operation of motor vehicles.

Association of work-related accidents with noise exposure in the workplace and noise-induced hearing loss based on the experience of some 240,000 person-years of observation

This retrospective study explores the association between occupational noise exposure at the time of hearing tests, permanent noise-induced hearing loss and work-related accident risk. Log-binomial analysis was used to first ascertain the association between study variables according to activity sector (North American Industry Classification System, NAICS) and accident context while controlling for age. Second part of the paper estimates the overall number of accidents attributable to occupational noise or the associated hearing loss (excess fraction). Study was carried on a sample of 52,982 male workers exposed to a minimum of 80 dBA on a daily basis and whose hearing was examined at least once between 1983 and 1996 by public health authorities of Quebec. These participants evidenced bilateral average hearing threshold levels at 3, 4 and 6 kHz ranging from normal (≤15 dB) to hearing loss in excess of 50 dB as a result of chronic occupational noise exposure (subjects otherwise otologically normal). The occupational accident count of these workers was derived from the individual histories registered with the Quebec workers’ compensation board for the 1983–1998 period. Results show an association between accident risk and worker's hearing sensitivity. For example, a hearing loss of 20 dB corresponds to a rise of accident risk equal to 1.14 when controlling for age and occupational noise exposure at the time of hearing tests. NAICS economic activity sectors where association is the most noticeable are “Metal Transformation”, “Metal Product Manufacturing” and “Transportation Equipment Manufacturing”. “Passive accidents” (PR per decibel of hearing loss = 1.008; CI 95 (1.007; 1.010)) and “same-level falls” (1.007; CI 95 (1.003; 1.010)) are the two accidents categories most strongly associated with hearing loss. Overall, 12.2% of accidents considered in this study were attributable to a combination of noise exposure in the workplace (≥90 dBA) and noise-induced hearing loss.

Evaluation of the risk of noise-induced hearing loss among unscreened male industrial workers

Variability in background risk and distribution of various risk factors for hearing loss may explain some of the diversity in excess risk of noise-induced hearing loss (NIHL). This paper examines the impact of various risk factors on excess risk estimates of NIHL using data from the 1968-1972 NIOSH Occupational Noise and Hearing Survey (ONHS). Previous analyses of a subset of these data focused on 1172 highly "screened" workers. In the current analysis, an additional 894 white males (609 noise-exposed and 285 controls), who were excluded for various reasons (i.e., nonoccupational noise exposure, otologic or medical conditions affecting hearing, prior occupational noise exposure) have been added 2066) to assess excess risk of noise-induced material impairment in an unscreened population. Data are analyzed by age, duration of exposure, and sound level (8-h TWA) for four different definitions of noise-induced hearing impairment, defined as the binaural pure-tone average (PTA) hearing threshold level greater than 25 dB for the following frequencies: (a) 1-4 kHz (PTA1234), (b) 1-3 kHz (PTA123), (c) 0.5, 1, and 2 kHz (PTA512), and (d) 3, 4, and 6 kHz (PTA346). Results indicate that populations with higher background risks of hearing loss may show lower excess risks attributable to noise relative to highly screened populations. Estimates of lifetime excess risk of hearing impairment were found to be significantly different between screened and unscreened population for noise levels greater than 90 dBA. Predicted age-related risk of material hearing impairment in the ONHS unscreened population was similar to that predicted from Annex B and C of ANSI S3.44 for ages less than 60 years. Results underscore the importance of understanding differential risk patterns for hearing loss and the use of appropriate reference (control) populations when evaluating risk of noise-induced hearing impairment among contemporary industrial populations.