Hearing Conservation Research Articles

Ototoxicity: Visualized in Concept Maps.

Ototoxicity refers to the damage to structures and function of the auditory-vestibular system caused by exogenous agents such as pharmaceuticals, chemicals, and ionizing radiation. There are many potentially ototoxic substances. For example, depending on how ototoxicity is defined, there are 200 to 600 medications that can cause damage to hearing and/or balance. Ototoxicity encompasses cochleotoxicity, vestibulotoxicity, and neurotoxicity. A variety of professional disciplines are involved in determining causation, prevention, and management of ototoxic effects. Research to identify and develop otoprotectants and otorescue agents is emerging and will translate basic scientific discovery into applications for use in hearing conservation programs, safety operations, and clinical care. Original concept maps are presented here to visually represent knowledge pathways, domains, and relationships essential to the understanding of ototoxicity.

Hearing protection devices and methods used for their evaluation: A military perspective

Introduction: Soldiers are regularly exposed to potentially harmful noise such as the constant noise of transport vehicle engines and the impulse noise of weapons. Impulse noise can be particularly hazardous, especially, for example, the high-intensity noise of artillery or shoulder-fired projectile launchers. After administrative and engineering controls, hearing protection devices (HPDs) are a cornerstone of hearing conservation programs. Yet selecting the appropriate protection for the various mission tasks must be done with care. HPDs can range from simple earplugs to high-tech options. Methods: Methods of characterizing the attenuation of HPDs against high-level impulse noise are complex and evolving. Results: For the soldier, the need to balance the degree of measured sound attenuation against interference with other auditory abilities – such as the need to hear soft sounds, to understand commands, or to localize sound – is a common dilemma. Discussion: This article outlines some of the challenges of assessing and choosing HPDs that keep soldiers safe from noise exposure with a view to helping those new to hearing conservation understand more about this important subject.

Evaluating the implementation fidelity of a community-based intervention to promote hearing conservation among farm and rural youth.

Noise-induced hearing loss is common among farm and rural youth. There is a lack of programs preparing this high-risk population to use hearing conservation strategies. Safety Days are 1-day workshops that teach 100,000 rural children safe farm practices in 400 sites across the USA annually. As part of a larger study for fourth graders, a hearing conservation lesson was delivered at 25 sites nationwide. However, the fidelity to the study-designed curriculum and quality of instruction was unknown. We examined whether community volunteers are capable of delivering, with adequate fidelity and quality, a planned intervention designed to increase use of hearing conservation strategies among farm and rural youth. We invited instructors (n = 22) to deliver a health lesson to fourth graders and provide lesson recordings. We developed instruments rating (i) fidelity of the teaching to the curriculum and (ii) quality of instruction. Initial instruments were modified based on the review for clarity, relevance, and conceptual fit; inter-rater reliabilities were .90 (content fidelity) and 1.00 (quality of instruction). Of seven recordings reviewed, mean fidelity to the planned curriculum was 1.51 (max score = 2), with nearly four fifths of lesson items fully addressed. Overall mean of rating of quality of instruction was 1.97 (out of 2). Fidelity to both content and quality of instruction was high. Results provide a model and support for use of community volunteers (with no special educational or experiential background) and fidelity testing as cost-effective strategies to provide sustainable programming for hearing conservation among farm and rural youth.

National occupational research agenda for hearing loss prevention

The National Institute for Occupational Safety and Health (NIOSH) has a mandate to conduct research on occupational safety and health. The research portfolio is organized by industrial sectors and cross-sectors for illnesses and injuries that are found in all sectors. The Hearing Loss Prevention research cross-sector council comprises representatives from government, labor organizations, academia, and industry representatives. The HLP council held several meetings throughout 2018 to determine research needs for occupational hearing loss prevention in the United States. Five topic areas were determined. (1) Provide input for policies and guidelines that will inform best practices for hearing loss-prevention efforts. (2) Develop effective, evidence-based education designed to improve hearing conservation program outcomes for exposed workers and management. (3) Develop, commercialize, and widely implement noise control solutions on jobsites in key industries. (4) Develop audiological tests for hearing loss prevention. (5) Improve occupational hearing loss surveillance. These topic areas will be discussed in detail to help motivate other researchers to join further our knowledge to prevent occupational hearing loss.

Pure-tone thresholds and the binaural masking level difference

Although several studies have examined the relationship between high-frequency pure-tone thresholds and the 500-Hz binaural masking level difference (BMLD), the results have not always been consistent. In this study, a retrospective analysis was conducted on an existing dataset from over 3000 military service members that included both pure-tone thresholds measured as part of their annual hearing conservation testing and a 33-trial clinical test of the BMLD. There was only a slight dependence of the 500-Hz BMLD on high-frequency pure-tone thresholds. For listeners with elevated pure-tone thresholds, this dependence was in good agreement with the findings of Jerger et al. [Arch. Otolaryngol. 110, 290–296 (1984)] and slightly larger than that reported by Wilson and Weakley [J. Am. Acad. Audiol. 16, 367–382 (2005)]. For listeners with near-normal hearing, the dependence of the 500-Hz BMLD on the 4-kHz pure-tone threshold was substantially less than that reported by Bernstein and Trahiotis [J. Acoust. Soc. Am. 140, 3540–3548 (2016)]. A possible explanation might be the degree of training offered to the subjects and procedural differences between clinical and laboratory techniques. [The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or U.S. Government.]

Evaluation of noise exposure and risk of hearing impairment in employees using communication headsets or headphones

The aim of the study was to assess the noise exposure and risk of noise-induced hearing loss (NIHL) among users of communication headsets (CHs) or headphones. Noise measurements and questionnaire surveys were carried out in 74 workers (aged: 31.8±7.3 years), including military aviation personnel (N = 12), transcribers (N = 18) and call center operators (N = 44). Sound pressure levels (SPLs) emitted by CHs (or headphones) were determined using the microphone in the real ear (MIRE) technique and artificial ear techniques according to PN-EN ISO 11904-1:2008 and CSA Z107.56-13, respectively. The risk of NIHL was evaluated in accordance with PN-ISO 1999:2000. The diffused-field-related A-weighted equivalent-continuous SPLs measured under CHs (or headphones) using the MIRE and artificial ear techniques reached values of 67-86 dB (10-90th percentile) and 68-89 dB (10-90th percentile), respectively. The study subjects used these devices 1.5-8 h (10-90th percentile) per day. Exposure to such noise levels for 40 years of employment causes the risk of hearing impairment (mean hearing threshold level for 2, 3 and 4 kHz > 25 dB) up to 10-12% (MIRE technique) or 19-22% (artificial ear technique). Individual daily noise exposure levels in study group varied 71-85 dB (10-90th percentile). A number of workers complained of problems with understanding speech in noisy environment (28.4%) and hearing whisper (16.2%) and experienced post-work temporary hearing symptoms (16.2-25.7%) as well. The users of CHs and headphones should be included in the hearing conservation program. Further studies are also needed among employees of other industries. Med Pr. 2019;70(1):27-52.

Hearing function of gold miners with and without a history of tuberculosis treatment: a retrospective data review

IntroductionSouth Africa has a high prevalence of co-existing tuberculosis and HIV. As ototoxicity linked to the treatments for these conditions occurs with concomitant exposure to other ear toxins such as hazardous noise exposure, it is important to investigate the combination impact of these toxins. Limited published evidence exists on the co-occurrence of these conditions within this population. ObjectivesThe objective of this study was to compare the hearing function of gold miners with (treatment group) and without (non-treatment group) the history of tuberculosis treatment, in order to determine which group had increased risk of noise induced hearing loss. Furthermore, possible influence of age and HIV in these two groups was examined. MethodsA retrospective record review of 102 miners’ audiological records, divided into two groups, was conducted, with data analyzed both qualitatively and quantitatively. ResultsFindings suggest that gold miners with a history of tuberculosis treatment have worse hearing thresholds in the high frequencies when compared to those without this history; with evidence of a noise induced hearing loss notch at 6000Hz in both groups. Pearson's correlations showed values between 0 and 0.3 (0 and −0.3) which are indicative of a weak positive (negative) correlation between HIV and hearing loss, as well as between hearing loss and age in this population. ConclusionsCurrent findings highlight the importance of strategic hearing conservation programs, including ototoxicity monitoring, and the possible use of oto-protective/chemo-protective agents in this population.

Happy ears for many years: selected papers from the 2018 Annual Conference of the National Hearing Conservation Association

As co-editors for this International Journal of Audiology (IJA) special supplement, we are pleased to introduce seven papers covering innovative, impactful research that represent a selected subset...

Knowledge, attitude, and practice of printing press workers towards noise-induced hearing loss.

Context:Noise-induced hearing loss (NIHL) is considered as a common occupational hazard among the industrial workers. The printing press is one of the common industrial set up where noise levels are often high. The awareness of people working in such a setup is generally less towards the hazards that is caused by noise exposure.Aim:The current study was designed to identify the knowledge, attitude, and practice (KAP) of printing press workers towards NIHL.Settings and Design:Cross-sectional study was carried using an adapted and validated KAP questionnaire. It was administered on 57 workers in Thiruvananthapuram, Kerala.Methods and Material:The study was carried out in two phases: phase I included the adaptation and validation of KAP questionnaire to printing press workers. Phase II comprised of the administration of the questionnaire among the study population. Statistical analysis used: Descriptive statistics was used to compile the results. To measure the internal consistency Cronbach’s alpha scale was used.Results:The responses obtained from workers showed inadequate knowledge, negative attitudes in certain subdomains and poor practice.Conclusions:The findings from the present study sheds light on the dearth of awareness in printing press workers on hearing conservation and need of training programs to educate the printing press workers towards the effects of NIHL.

The combined effects of occupational exposure to noise and other risk factors - a systematic review.

Purpose:Noise-induced health effects exacerbate by many other risk factors. This systematic review aims at shedding light on the combined effects of co-exposure to occupational noise and other factors.Material and Methods:A literature search in Web of Science, Scopus, PubMed, Science Direct, and Google Scholar, with appropriate keywords on combined effects of occupational noise, and co-exposure to noise and other factors, revealed 7928 articles which were screened by two researchers. A total of 775 articles were reviewed in full text. We found 149 articles that were relevant and had sufficient quality for analysis.Results:We identified 16 risk factors that exacerbate occupational noise-induced health effects. These factors were classified into four groups: chemical (carbon monoxide (CO), solvents, heavy metals, and other chemicals), physical (lighting, heat, vibration, and cold), personal (age, gender, genetics, smoking, medication, contextual diseases) and occupational (workload and shift work). Hearing loss, hypertension, reduced performance, and cardiovascular strains, are the most important risk factors combined effects due to concurrent exposure to noise and other risk factors.Conclusion:Evidences of combined effects of solvents, vibration, heavy metals, CO, smoking, chemicals, aging, heat, and shiftwork were respectively stronger than for other factors. Most of the studies have investigated only the combined effects of risk factors on hearing, and the evidence for non-auditory effects is still limited, and more studies are warranted. Therefore, in the Hearing Conservation Programs, besides noise, aggravating factors of noise effects should also be taken into account.

Hearing Difficulties and Tinnitus in Construction, Agricultural, Music, and Finance Industries: Contributions of Demographic, Health, and Lifestyle Factors.

High levels of occupational noise exposure increase the risk of hearing difficulties and tinnitus. However, differences in demographic, health, and lifestyle factors could also contribute to high levels of hearing difficulties and tinnitus in some industries. Data from a subsample (n = 22,936) of the U.K. Biobank were analyzed to determine to what extent differences in levels of hearing difficulties and tinnitus in high-risk industries (construction, agricultural, and music) compared with low-risk industries (finance) could be attributable to demographic, health, and lifestyle factors, rather than occupational noise exposure. Hearing difficulties were identified using a digits-in-noise speech recognition test. Tinnitus was identified based on self-report. Logistic regression analyses showed that occupational noise exposure partially accounted for higher levels of hearing difficulties in the agricultural industry compared with finance, and occupational noise exposure, older age, low socioeconomic status, and non-White ethnic background partially accounted for higher levels of hearing difficulties in the construction industry. However, the factors assessed in the model did not fully account for the increased likelihood of hearing difficulties in high-risk industries, suggesting that there are additional unknown factors which impact on hearing or that there was insufficient measurement of factors included in the model. The levels of tinnitus were greatest for music and construction industries compared with finance, and these differences were accounted for by occupational and music noise exposure, as well as older age. These findings emphasize the need to promote hearing conservation in occupational and music settings, with a particular focus on high-risk demographic subgroups.

Logical operating model of the hearing conservation program for workers

ABSTRACT Purpose: to validate the contents of an operating model of hearing conservation programs. Methods: this is a documentary and methodological research, in which the operating model was evaluated by ten experts in audiology, through the analysis of the activities developed in the implementation of the hearing conservation program. The components were analyzed according to the formula that determines the content validation index by item, and the operational logical model as a whole, according to the content validation formula by scale level. The items were considered valid when agreement among participants reached more than 80%. Results: the operating model was structured in 4 (four) dimensions, namely: (1) Management; (2) Environmental Control; (3) Attention to Hearing Health; (4) Evaluation of Efficacy and Efficiency. Each dimension corresponds to a set of activities (referred to as processes), and their respective results expected. For the structure of the program, considering its set of dimensions, material, organizational and human resources were listed. Conclusion: the proposed operating model and its components proved to be valid in their relevance and comprehensibility, offering support and applicability in evaluating the effectiveness and efficiency of the program.

A proposed preliminary model for monitoring hearing conservation programmes in the mining sector in South Africa

A proposed preliminary model for monitoring hearing conservation programmes in the mining sector in South Africa

Relationship Between Subjective Reports of Temporary Threshold Shift and the Prevalence of Hearing Problems in Military Personnel.

Traditional hearing conservation programs are based on the premise that noise dose, as measured by the time-weighted average noise level, is the primary risk factor associated with occupational hearing loss and that permanent threshold shifts are the most relevant outcome measures for determining when a noise-related hearing loss has occurred. However, recent studies in animal models have suggested that significant neurological damage to the hearing system can occur from noise exposures even when they are not severe enough to result in permanent threshold shifts. This has led to a number of studies attempting to relate subjective measures of noise exposure to subjective measures of hearing difficulty and suprathreshold measures of hearing performance (e.g., speech-in-noise tests). In this study, 3,330 U.S. service members volunteered to complete a survey on noise exposure, subjective hearing complaints, and tinnitus in conjunction with their annual hearing tests. Two questions were also included about the frequency and duration of temporary hearing losses that may have been experienced by the service member. The results show that subjective reports of temporary threshold shifts were substantially more predictive of tinnitus and other hearing complaints than more traditional questions based on the frequency of noise exposure.

Evaluation of the Impact of Tinnitus on Health-Related Quality of Life amid Sawmill Workforces

Background: Tinnitus is the phantom aural perception of sound lacking an exterior stimulus, a sub-type of auditory hallucination and it is a common sensation among noise-exposed employees. It is a symptom, not an illness. Tinnitus can be extremely perplexing for its subjects and it may perhaps dis-turb their health-related quality of life (HR-QoL) if exposed to extreme noises in many ways. Objective: This study is intended to discover the effects and pattern of tinnitus on health-related quality of life (HR-QoL) amid noise-exposed saw mill workforces. Method: This study was a prospective and public-centered cross-sectional study, including 510 sawmill personnel. 510 directorial staff was used as the control. Health-related quality of life (HR-QoL) of all subjects was assessed with the WHO Quality of Life brief questionnaire. Self-reported tinnitus morbidity was assessed by means of the Tinnitus Handicap Inventory. A correlation was established amid health-related quality of life scores and tinnitus severity scores. Result: There were 510 sawmill employees enlisted into the study, out of which 490 were men and 20 were women with control of the same age and sex. The mean age was 36.85 ± 7.68 years for the sawmill workers and 35.75 ± 8.65 years for the control group (t = 1.02, P = 0.275). The mean tinnitus score for the sawmill workers was 20.80 ± 2.56. Out of the 510 sawmill workers, 52 (10.2%) had tinnitus and one of the controls had tinnitus. The mean health-related quality of life scores were 62.20 ± 8.62 and 72.56 ± 5.98 for the sawmill workers and control group respectively. There was a substantial and remarkable difference between the health-related quality of life of the sawmill workers and the control group (P < 0.05). Also, it was observed that there was a noteworthy drop in the overall physical and psychological domains of the health-related quality of life scores with an increase in work environment noise level among sawmill employees and no major alteration was observed in the social and environmental aspects of the quality of life scores with change in occupational noise gains. Conclusion: The prevalence of tinnitus from this study was found to be 10.20% and an upsurge in tinnitus rigorousness was seen to be related with a substantial drop in physical, psychological and social domains of the health related quality of life. We highly endorse hearing conservation programmes and use of personal protective equipments for sawmills workers which will aid to decrease the effects of exposure to loud noise. Those sawmill labors already having tinnitus must attempt to go for treatment.

Research on the Occupational Noise Exposure Health Risk Management Standard

To prevent and control the occupational noise hazard, procedures and methods of risk assessment and management of occupational noise hazard in the workplaces have been proposed as technical guidelines in the new standard “Risk Management Guidelines for Noise Occupational Disease Hazard” based on the current status and technical requirements of occupational noise hazard in China. These guidelines are consist of the risk assessment method which partly adopts the method given by the latest ISO 1999:2013(E) “Acoustics — Estimation of noise induced hearing loss”, and the risk management procedures which are mainly based on the US NIOSH’s recommended standard “Occupational Noise Exposure Revised Criteria 1998”. The guidelines put forward procedures and technical contents such as the risk management program, occupational noise exposure quantitative risk evaluation procedures and methods, and the implementation details of a hearing conservation plan. The standard is based on the current status and technical requirements of the occupational noise hazard in China, in accordance with the relevant national laws, regulations and standards related to hearing protection and supervision and management of the occupational hazard of construction projects. It can be used as guidelines for occupational noise exposure evaluation and risk assessment in various kinds of workplaces that produce productive noises and for exposure level monitoring, effectiveness evaluation of noise control measures, occupational health management, supervision and inspection.

Efficacy of hearing conservation education programs for youth and young adults: a systematic review

BackgroundMany youth and young adults experience high noise exposure compounded by lack of access to hearing health education. Although the need for hearing health education programs is evident, the efficacy of these programs for youth is unclear. We evaluated the literature for efficacy of various hearing conservation programs aimed at youth and young adults, and analyzed their strengths and limitations.MethodsStudies reporting results of hearing conservation or hearing loss prevention programs with youth or young adults, using randomized controlled trials, quasi-experimental designs, experimental design, or qualitative research, and published in peer-reviewed journals in English between 2001 and 2018 were included. Studies were found through searches of selected literature databases (i.e., PubMed, Google Scholar, NIOSH Toxline, and Scopus). Identified publications were assessed for relevance, and data were extracted from the studies deemed relevant.ResultsA total of 10 studies were included. Very little evidence of efficacy of hearing conservation educational programs was found in these studies. Several methodological limitations including lack of rigorous study designs, inadequate power, and application of inappropriate statistical analysis were noted. Some use of technology in programs (e.g., smartphone apps, mobile phone text messages, and computers) was observed, but conclusions as to the effectiveness of these tools were limited by the small number of studies and small sample sizes.ConclusionsThe number of studies of educational hearing conservation programs for youth and young adults was low. The efficacy of the program was not reported in most studies, and it is difficult to draw public health conclusions from these studies due to their multiple methodological limitations. While use of technology in hearing conservation educational programs offers promise, its effectiveness has not been studied.

Comparative assessment of shift in hearing threshold among handicraft operatives in India

This case-control exploratory study is first of its kind to assess the noise exposure and loss in hearing threshold (HT) due to the occupational use of hand tools used for handicraft work. Sixty male participants involved in different crafts trade and a reference group of 50 office workers were selected. The sound pressure levels under actual work conditions were measured as per the method outlined in IS 7194:1994. The mean equivalent sound pressure level was quite high (96.37 dB(A)), exceeding the exposure limit of 90 dB(A). Audiometric tests were conducted to compare the HT between both the groups. In agreement with dose consumed, the exposed workers exhibit moderate hearing impairment in the frequency range of 1500–6000 Hz. The association of HT at different frequencies among occupation were detected using post-hoc multiple comparisons. 95% of the workers showed hearing handicap at some level and noise-induced hearing loss increases with higher age and experience. Interventions in the hand tools, implementation of hearing conservation programmes and practice of personal protective equipments have been suggested.Practitioner Summary: As the primary outcomes, comparative assessment of the shift in hearing threshold was analyzed in anticipation to develop a better work system. Results from the study report that the sound pressure level was fairly high and 95% of the handicraft operatives showed hearing handicap at some level.

Longitudinal changes in hearing threshold levels for noise-exposed military personnel.

Military personnel are exposed to variable and sometimes very high noise in their professional environment. The aim of this study is to evaluate through a longitudinal study if our hearing conservation program has to be adapted to consider specific interventions for subgroups of our military population still subject to a higher risk of hearing loss. We conducted a retrospective longitudinal study in 2015-2016 to describe the evolution of hearing threshold levels of military personnel as measured during periodic audiometric screening over a period of 6years (2009-2014) after the implementation of our hearing conservation program. A linear mixed model explored the relationship of pure-tone average (PTA) on 3, 4 and 6KHz with probability of noise exposure, gender, age at baseline, time since baseline, hearing loss at baseline and ear. For 18,672 military individuals, our results show a small but statistically significant increase of 0.08dB per year in PTA on 3, 4 and 6KHz over the 6-year period that is consistently decelerating as a function of time. An additional annual increase of hearing thresholds due to higher age and moderate and high probability of exposure to noise was also found. No major adaptation of our hearing conservation program is required but efforts should be strengthened to better evaluate and counsel older individuals and subjects exposed to noise regarding avoidance of noise and correct use of personal hearing protection.

Association between audiometric patterns and probabilities of cardiovascular diseases.

ObjectivesThe aim of this study was to analyze the progression of the audiometric pattern of serial screening tests in companies with hearing conservation program (HCP) to clinical audiometric tests to identify individuals more susceptible to develop cardiovascular diseases (CVDs). The procedure is based on the analysis of various audiometric patterns that have been demonstrated to have a statistically significant relation to certain CVDs. Identifying these individuals, based on pattern progression of hearing loss, could result in earlier detection to prevent disease or decrease its morbidity.Study designUsing the data from the clinical and screening audiograms, pattern analysis was performed and statistical analysis using Fisher's exact test, odds ratios and P values were used to calculate the confidence intervals.MethodsThe analysis was based on potential risk factors related to CVD in 29 cohorts of 10,105 subjects. Of these, a total of 704 subjects also had clinical audiometric tests and examination by an ENT to verify the exactitude of the screening test questionnaire and pattern relation with the clinical audiogram.ResultsA first analysis was made on 704 subjects who had clinical evaluation and clinical audiometric tests showed results comparable to those of Friedland. A correlation between the questionnaire of the clinical and the self‐reporting screening tests questionnaires was performed and showed a correlation between the following risk factors: diabetes, hypertension, hyperlipidemia and smoking. Analysis of the progression of audiometric patterns suggested a relationship with the predictive probabilities of developing CVDs.ConclusionProgression toward low‐frequency hearing loss patterns provides early identification of patients whose audiometric pattern progression suggests increased probability of developing CVDs. The treating physician, by prescribing further investigations, could potentially prevent or reduce the morbidity of these diseases.Level of EvidenceIII