Methodological Issues When Comparing Hearing Thresholds of a Group With Population Standards: The Case of the Ferry Engineers

Audiograms and Prevalence of Hearing Loss in U.S. Children and Adolescents 6-19 Years of Age

PURPOSE

The aim of this study was to determine median audiograms and prevalence of hearing loss for U.S. 6- to 19-year-olds.

METHOD

U.S. national audiometric data for 2,709 six- to 19-year-olds from the National Health and Nutrition Examination Survey 2017-2020 were analyzed. Analyses were primarily descriptive and relied on distribution-free medians, cumulative distribution functions (CDFs), and population-weighted prevalence estimates. Differences between CDFs were examined using Cohen's h effect size. Results are presented for the age range of 6-19 years. Main effects of sex, age, and race/ethnicity were examined.

RESULTS

Differences in the audiograms between the sexes and among the various race/ethnicity groups were minor, but age group differences were notable. Pure-tone thresholds at 500 and 8000 Hz for the 6- to 9-year age group were 3-5 dB higher (worse) than those of the other age groups. The overall prevalence of hearing loss among 6- to 19-year-olds, defined as either of the pure-tone averages (PTAs) for 500, 1000, and 2000 Hz (PTA512) or 3000, 4000, 6000, and 8000 Hz (PTA3468k) exceeding 15 dB HL in either ear, was 11.24% (95% confidence interval [10.00%, 12.48%]). Binary logistic regression analyses found the odds of hearing loss to be significantly higher for individuals from families with a low income as well as for those with abnormal otoscopy or abnormal tympanometry.

CONCLUSIONS

For children and adolescents in the United States, hearing was unaffected by differences in sex and race/ethnicity, with only age impacting pure-tone thresholds and only at the lowest (500 Hz) and highest (8000 Hz) frequencies examined. The overall prevalence of hearing loss was about 11%.

Demographic and Audiological Characteristics of Candidates for Over-the-Counter Hearing Aids in the United States

OBJECTIVES

This report presents descriptive data on the demographic and audiological characteristics of US adults with perceived mild-to-moderate hearing loss, the primary candidates for over-the-counter (OTC) hearing aids.

DESIGN

The analyses are descriptive and present population-weighted responses for various self-reported demographic and audiological variables for adults with mild or moderate perceived hearing trouble. Results of pure-tone audiometry and immittance measures are also presented. Nationally representative datasets from the National Health and Nutrition Examination Surveys (NHANES) for 2011 to 2012, 2015 to 2016, and 2017 to 2020, the three most recent NHANES datasets with audiological information, were used.

RESULTS

The NHANES datasets indicated that there are 49.5 million adults in the United States with perceived mild-to-moderate hearing trouble. Results indicated that OTC hearing-aid candidates are most frequently 50 to 69 years of age, married, and identify as non-Hispanic White race/ethnicity. Most of these individuals graduated from high school, had several risk factors for hearing loss, had not had a hearing test in the past 5 years, and had never used hearing aids or assistive listening devices previously. The typical audiometric profile was a bilaterally symmetrical sloping hearing loss with slight to mild hearing loss above 2000 Hz. Group data showed normal immittance measures and absence of otoscopic abnormalities except for the presence of excessive (not impacted) cerumen in about 13% of the OTC hearing-aid candidates.

CONCLUSIONS

Tens of millions of US adults have perceived mild-to-moderate hearing trouble but have not pursued assistance, either through obtaining a hearing test or acquiring prescription hearing aids.

Hearing thresholds for "otologically normal" adults from the National Health and Nutrition Examination Surveys 2011-12 and 2015-16

Hearing threshold levels (HTLs) get worse with advancing age in adults. Publications of nationally representative data from U.S. adults have been confined to HTLs from unscreened individuals. ISO 7029:2017 provides equations for the hearing loss of adults of various ages. Equations were generated from a synthesis of international studies of HTLs for "otologically normal" or screened adults. No nationally representative data for screened U.S. adults were included in the ISO synthesis. This study investigated three different levels of screening rigor, referred to here as Screened, Screened+, and Screened++. Median HTLs are provided for Screened (N = 1545) and Screened++ (N = 795) groups from the National Health and Nutrition Examination Surveys for 2011-12 and 2015-16, the two most recent surveys of adults from 20 to 69 years of age with audiograms. Median HTLs from the Screened and Screened++ groups differed slightly between the sexes, were not affected by race/ethnicity, and increased substantially with age. For young adults, there were no differences in HTLs between screened (any level) and unscreened adults, but such differences in HTLs increased with advancing age, especially at higher frequencies. The default power-function model from ISO 7029:2017 did not provide a good description of the median age-associated HTLs from screened U.S. adults.

Hearing Thresholds for Unscreened U.S. Adults: Data From the National Health and Nutrition Examination Survey, 2011-2012, 2015-2016, and 2017-2020

Hearing threshold levels (HTLs) at 500-8,000 Hz from the National Health and Nutrition Examination Survey (NHANES) 2011-2012, 2015-2016, and 2017-2020 were analyzed for males and females ranging in age from 20 to 80-plus years (N = 8,795). HTLs for the 10th, 25th, 50th, 75th, and 90th percentiles are provided for males and females. Equations were generated to describe median HTLs as a function of age at each frequency. The medians generated for this unscreened dataset of U.S. adults were compared to those in Table B.3 of ISO 1999 (2013), which came from analyses of the NHANES 1999-2006 datasets. The ISO 1999 values were found to be slightly higher (worse) at several frequencies. The ISO 1999 (2013) median HTLs were 2 to 5 dB worse at 500 Hz for males and females and 2 to 8 dB worse at 4,000 and 6,000 Hz for males than the updated NHANES estimates. As in prior analyses of NHANES data, HTLs worsened with age, were better for females than males, and were better for Non-Hispanic Blacks than for Non-Hispanic Whites. The latter difference was observed for both males and females, was confined to frequencies above 2,000 Hz, and widened with increasing age.

Gender-specific hearing loss in German adults aged 18 to 84 years compared to US-American and current European studies

INTRODUCTION

From an epidemiological point of view, the increase of pure-tone hearing thresholds as one aspect of biological ageing is moderated by societal factors. Since health policies refer to empirical findings, it is reasonable to replicate population-based hearing surveys and to compare estimates for different birth cohorts from the same regions or, conversely, for the same birth cohorts from different regions.

METHODS

We pooled data from two independent cross-sectional German studies conducted between 2008 and 2012 and including 3105 adults. The increase of thresholds, the prevalence and risk of hearing impairment (HI) by age and gender were compared to results reported for European and US-American studies that were carried out at about the same time. Since these studies differed with regard to the age limits, the statistical approaches and, importantly, their definitions of HI, data adjustments were performed to enable the comparison.

RESULTS

Overall, 15.5% of the participants in the German studies showed a pure-tone average at 0.5, 1, 2, and 4 kHz in the better ear (PTA) greater than 25 dB HL and 8.6% had a PTA of at least 35 dB HL. Based on one-to-one comparisons, the German estimates demonstrated a good agreement to a large Dutch study and with some reservations to a Swedish study, but considerable differences to US-American results. Comprehensive comparisons of the within-study gender differences showed that age-related HI was less and the gender gap was markedly smaller in Europe compared to the US due to the lower HI in males found in the European studies.

CONCLUSION

Discrepancies in measurement procedures, conditions, and equipment that complicate the comparison of absolute HI estimates across studies play no or only a marginal role when comparing relative estimates. Hence, the gender gap differences reviewed in this analysis possibly stem from societal conditions that distinguish societies commonly labeled modern industrialized western countries.

Hearing among male firefighters: a comparison with hearing data from screened and unscreened male population

We investigated whether hearing loss is associated with firefighting. We conducted cross-sectional study comparing hearing threshold levels (HTLs) of 912 male firefighters with two hearing databases obtained from an otologically normal male Korean population (KONP) and a non-industrial noise-exposed male Korean population (KNINEP), considering age and the main roles of firefighters. Firefighters' age-adjusted HTLs were significantly worse than those of KONP (prevalence ratio (PR)=5.29, P<0.001)but not different from those of KNINEP (PR=0.99, P=0.550). Rescuers (PR=1.005, P<0.001) had worse hearing than the KNINEP after age adjustment. Comparison of firefighters' HTLs (50th and 90th percentiles) with those of KONP and KNINEP by age and frequency showed that firefighters' HTLs had significant increases (poorer hearing) across most age groups and frequencies compared with KONP. Compared with KNINEP, firefighters' HTLs were worse in the younger age groups (<45 years) but not different in the older age groups (>45 years). In conclusion, the hearing thresholds of younger firefighters and rescuers were worse than expected by normal aging alone. Future research should include longitudinal studies to consider variable risk factors, such as military service, smoking, and so on.

Noise and age-related hearing loss: a study of 40 123 gold miners in South Africa

OBJECTIVE AND DESIGN

This retrospective cohort study aimed to describe the differential effect of noise exposure and age-related hearing loss in a large sample of gold miners in South Africa.

STUDY SAMPLE

Audiological data of 40 123 South African mine workers were investigated. Data of a non-noise-exposed control group (n = 6162) and group exposed to underground noise (≥ 85 dB A (TWA) (n = 33 961) were included. Within these two larger noise-exposed groups two homogenous exposure groups (HEG) were also selected for analyses, namely the driller group (n = 4399) and the administration group (administrative workers) (n = 2211). Participants were categorized in terms of noise exposure, age, and race.

RESULTS

Significantly different thresholds (worse for underground noise group) with respect to the median for all frequencies after adjusting for age was evident between the noise-exposed and control groups (ANCOVA). The largest differences in hearing thresholds between the noise-exposed and control groups were observed at 3 and 4 kHz in the age group 36 to 45 years. Administration and driller group differed significantly (driller group worse results) with respect to the mean LFA512 and HFA346 after adjusting for age (ANCOVA). Black males had significantly better high-frequency hearing compared with white male counterparts but significantly worse low-frequency hearing.

CONCLUSION

Age was the most important influence on hearing thresholds for the noise and control groups. Race was shown to be a very significant factor determining susceptibility to NIHL and ARHL.

Hearing evaluation of patients with head and neck cancer: Comparison of Common Terminology Criteria for Adverse Events, Brock and Chang adverse event criteria in patients receiving cisplatin

BACKGROUND

The purpose of this study was to compare Common Terminology Criteria for Adverse Events (CTCAE), Brock and Chang hearing loss grading in patients with head and neck cancer receiving cis-diamminedichloroplatinum (CDDP). Endpoints were baseline distribution of hearing loss, interobserver consistency, and sensitivity to hearing loss after CDDP treatment.

METHODS

Four hundred sixty single ear audiograms in 110 patients with head and neck cancer were graded. Hearing loss at baseline, interobserver agreement rates, and changes in hearing loss after CDDP were evaluated.

RESULTS

The Chang and Brock tools' baseline hearing loss distribution was concentrated at grade 0 (57% and 41%, respectively), whereas 47%, per the CTCAE, had grade 3 baseline hearing loss. Interobserver agreement was highest for the Brock scale (≥90%) followed by the Chang (≥89%) and CTCAE (≥75%) scales. Detection of change after CDDP was highest for Chang (48%) followed by Brock (45%) and the CTCAE (32%).

CONCLUSION

The Brock and Chang tools may be superior to the CTCAE in patients with head and neck cancer receiving CDDP using baseline hearing loss distribution, interobserver agreement, and detection of hearing loss grade change as performance indicators.

Hearing threshold levels at age 70 years (65-74 years) in the unscreened older adult population of the United States, 1959-1962 and 1999-2006

OBJECTIVES

To provide hearing threshold percentiles from unscreened older adults for creating new Annex B reference standards.

DESIGN

Percentiles are calculated, and 95% confidence intervals for medians from two U.S. surveys are compared graphically.

RESULTS

Median thresholds are lower (better) in the 1999-2006 National Health and Nutrition Examination Survey for men across all frequencies except 1 kHz. Results for women are similar; however, there is more overlap in confidence intervals across frequencies.

CONCLUSIONS

The prevalence of hearing impairment in older adults, age 70 years (65-74 years), is lower in 1999-2006 compared with 1959-1962, consistent with our earlier findings for younger adults.

Relative risk of elevated hearing threshold compared to ISO1999 normative populations for Royal Australian Air Force male personnel

OBJECTIVE

This paper introduces a new method to calculate relative risks of elevated hearing thresholds, at various ages and frequencies, between a study population and ISO1999:2003: Annex A Screened, Annex B Unscreened and ISO1999 Section 5.3 adjustment for noise exposure using Annex A Screened data. We demonstrate this method on a study population of male Royal Australian Air Force personnel.

STUDY DESIGN

Using a retrospective cohort design, hearing thresholds were assessed in 583 F-111 aircraft maintenance personnel, 377 technical-trade comparisons and 492 non-technical comparisons using pure-tone audiometry. A quantile regression model was used determine whether an association exists between median hearing thresholds and F-111 maintenance, adjusting for possible confounders. The new method involves using quantile regression models with bootstrapped standard errors to estimate percentiles for the study population and thus determine the probability of a greater than 25 dB hearing threshold. This was done for the three ISO datasets as follows; for the ISO1999 Annex A screened population data the formula provided allows the calculation of these probabilities. ISO1999 Annex B unscreened population data only provides the values for the 10th, 50th and 90th percentiles at ages 30, 40, 50 and 60 only, therefore it was necessary to fit a curve to these values in order to estimate the probabilities. For ISO1999 Section 5.3 adjustment for noise exposure population we used the Annex A screened population data plus the formula. The probabilities were then divided to give the relative risks of a greater than 25 dB hearing threshold, at various ages and frequencies.

RESULTS

While no difference was observed between the three groups, the model identified a number of significant confounders, namely tinnitus, smoking, diabetes and the use of anti-depressant medications. Relative risks were high at frequencies 2 kHz and less for the study population of all ages compared to ISO A screened data. The increased relative risks at 4 and 6 kHz give the appearance of a "noise notch" for ages 30 and 40 years. The comparison with the ISO B unscreened data are significantly less than one for frequencies above 2 kHz, particularly for young men and greater than one less than 2 kHz. The relative risks for the comparison to the ISO A screened data with ISO 5.3 adjustments, are highest for young men decreasing with age, with the highest relative risk are at frequencies less than 2 kHz.

CONCLUSIONS

This paper demonstrates a new method for quantifying the probability of a clinically relevant hearing loss and the relative risk of the loss due to a risk factor. Prior to this, researchers were reduced to simplistic methods such as visual comparison of deciles which did not enable the estimation of risk. The new method can use all observed hearing thresholds per study participant, adjust for known confounding factors such age and gender, and calculate the relative risk of a clinically relevant increase in hearing threshold due to a risk factor of interest.

A retrospective analysis of noise-induced hearing loss in the Dutch construction industry

Purpose

Noise exposure is an important and highly prevalent occupational hazard in the construction industry. This study examines hearing threshold levels of a large population of Dutch construction workers and compares their hearing thresholds to those predicted by ISO-1999.

Methods

In this retrospective study, medical records of periodic occupational health examinations of 29,644 construction workers are analysed. Pure-tone audiometric thresholds of noise-exposed workers are compared to a non-exposed control group and to ISO-1999 predictions. Regression analyses are conducted to explore the relationship between hearing loss and noise intensity, noise exposure time and the use of hearing protection.

Results

Noise-exposed workers had greater hearing losses compared to their non-noise-exposed colleagues and to the reference population reported in ISO-1999. Noise exposure explained only a small proportion of hearing loss. When the daily noise exposure level rose from 80 dB(A) towards 96 dB(A), only a minor increase in hearing loss is shown. The relation of exposure time and hearing loss found was similar to ISO-1999 predictions when looking at durations of 10 years or more. For the first decade, the population medians show poorer hearing than predicted by ISO-1999.

Discussion

Duration of noise exposure was a better predictor than noise exposure levels, probably because of the limitations in noise exposure estimations. In this population, noise-induced hearing loss was already present at the beginning of employment and increased at the same rate as is predicted for longer exposure durations.

Presbycusis phenotypes form a heterogeneous continuum when ordered by degree and configuration of hearing loss

Many reports have documented age-by-frequency increases in average auditory thresholds in various human populations. Despite this, the prevalence of different patterns of hearing loss in presbycusis remains uncertain. We examined 'presbycusis phenotypes' in a database of 960 subjects (552 female, 408 male, 18-92 years) that each had 30 measures of peripheral hearing sensitivity: pure tone audiograms for left and right ears from 0.25 to 8 kHz and DPOAE for each ear with F(mean)=1-6.4 kHz. Surprisingly, the hearing phenotypes did not naturally separate into discrete classes of presbycusis. Principal component (PC) analysis revealed that two principal components account for 74% of the variance among the 30 measures of hearing. The two components represent the overall degree (PC1) and configuration of loss (Flat vs. Sloping; PC2) and the phenotypes form a continuum when plotted against them. A heuristic partitioning of this continuum produced classes of presbycusis that vary in their degree of Sloping or Flat hearing loss, suggesting that the previously reported sub-types of presbycusis arise from the categorical segregation of a continuous and heterogeneous distribution. Further, most phenotypes lie intermediate to the extremes of either Flat or Sloping loss, indicating that if audiometric configuration does predict presbycusis etiology, then a mixed origin is the most prevalent.

Estimation of equivalent noise exposure level using hearing threshold levels of a population

OBJECTIVES

Noise-induced hearing loss (NIHL) is costly in both human and economic terms. One means of reducing NIHL is to apply engineering controls to hazardous noise sources. To trade off the cost of engineering controls against the total direct monetary costs incurred by NIHL, a means of predicting the amount of NIHL that will be incurred over the life-cycle of a hazardous noise source is necessary. A widely known algorithm for the prediction of NIHL is published in ANSI S3.44-1996. However, the algorithm inputs, noise exposure level and duration, may be difficult to determine in some cases. This paper describes the conceptual basis of an approach for using ANSI S3.44-1996 to predict hearing thresholds in a population even when noise exposure levels and durations are not precisely known, and demonstrates the initial application of this approach to a single military population.

DESIGN

Retrospective data were obtained on the hearing-threshold levels, demographic characteristics, and noise exposure history of 250 male U.S. Navy machinists' mates. A maximum-likelihood fitting procedure was developed in which the noise level input to the algorithm was varied in order to determine the noise level that best accounted for all of the data.

RESULTS

The maximum likelihood fitting produced a value for the noise level input of approximately 93 dBA, with a standard error of approximately 0.3. The low standard error virtually eliminates any estimate above 94 or below 92 dBA, and indicates that a good fit to the data was achieved.

CONCLUSIONS

This research demonstrates the feasibility of calibrating the algorithm to an individual population, even when noise exposure level or duration is not precisely known. Future work will focus on validating and generalizing this approach so that it may be used to predict hearing-threshold levels in various populations. Such an approach may be used in calculating potential cost savings in compensable hearing loss due to the application of noise control solutions.