Evaluation of the Increased Accident Risk From Workplace Noise

Effects of hearing protector devices on speech intelligibility: the importance of individualized assessment

Objectives. This study aimed to compare speech intelligibility in noise with and without hearing protection devices (HPDs). Methods. Fifty-one workers were distributed into three groups: noise-induced hearing loss group (NIHLG), normally hearing noise-exposed group (NG) and normally hearing non-exposed to noise group (CG). A free field system was used to emit monosyllables (65, 70 and 75 dB) and pink noise in different signal-to-noise ratios (SNRs) (0, -5, -10 and -15). Results. In situations with HPDs, all groups showed a decrease in the percentage of correct responses with an increase in noise level. The HPD had little effect on speech intelligibility in the NIHLG and NG. Considering the effect caused by the HPD on speech intelligibility, it was observed that the group with the greatest loss was the CG for SNRs of -5, -10 and -15. Conclusion. Although speech intelligibility is influenced by the hearing threshold, the noise level and SNR are crucial for good speech intelligibility, either with or without an HPD. It is highlighted that the NG had worse results when compared with the CG, which may indicate changes in the auditory pathway resulting from continuous noise exposure, even in the absence of changes in the audiometric thresholds.

Effect of wearing hearing protectors on the audibility of railway warning signals - an experimental study

The effect of wearing hearing protectors on the audibility of warning signals has been evaluated for three specific railway-related jobs: track workers, train drivers and platform agents. Masked thresholds were measured in the laboratory, on railway agents with normal hearing, using warning signals and background noises typical of each job. Out of the 36 situations tested in total, statistical analyses showed that wearing earplugs improves the perception in 11 situations, deteriorates the perception in 10 situations and has no significant effect in 15 situations (as compared to no hearing protector). The deteriorations essentially concern signals which have no (or not enough) energy in the low-frequency range (f< 1500 Hz) when they have to be heard in background noises which dominate in the low-frequency range. To prevent the deteriorations, these signals could be modified by adding some energy in the low-frequency range (f< 1500 Hz).

Noise exposure and cognitive performance: A study on personnel on board Royal Norwegian Navy vessels

Prior research shows that work on board vessels of the Royal Norwegian Navy (RNoN) is associated with noise exposure levels above recommended standards. Further, noise exposure has been found to impair cognitive performance in environmental, occupational, and experimental settings, although prior research in naval and maritime settings is sparse. The aim of this study was to evaluate cognitive performance after exposure to noise among personnel working on board vessels in the RNoN. Altogether 87 Navy personnel (80 men, 7 women; 31 ± 9 years) from 24 RNoN vessels were included. Noise exposure was recorded by personal noise dosimeters at a minimum of 4 h prior to testing, and categorized into 4 groups for the analysis: <72.6 dB(A), 72.6-77.0 dB(A), 77.1-85.2 dB(A), and >85.2 dB(A). The participants performed a visual attention test based on the Posner cue-target paradigm. Multivariable general linear model (GLM) analyses were performed to analyze whether noise exposure was associated with response time (RT) when adjusting for the covariates age, alertness, workload, noise exposure in test location, sleep the night before testing, use of hearing protection device (HPD), and percentage of errors. When adjusting for covariates, RT was significantly increased among personnel exposed to >85.2 dB(A) and 77.1-85.2 dB(A) compared to personnel exposed to <72.6 dB(A).

Noise as an explanatory factor in work-related fatality reports

Noise exposure in the workplace is a common reality in Québec, Canada as it is elsewhere. However, the extent to which noise acts as a causal or contributive factor in industrial work-related accidents has not been studied thoroughly despite its plausibility. This article aims to describe the importance or potential importance, during investigations looking into the specific causes of each work-related fatal accident, of noise as an explanatory factor. The written information contained in the accident reports pertaining to contextual and technical elements were used.

The study used multiple case qualitative content analysis. This descriptive study was based on the content analysis of the 788 reports from the Commission de la santé et de la sécurité du travail du Québec [Workers’ Compensation Board (WCB)] investigating the fatal work-related accidents between 1990 and 2005. The study was descriptive (number and percentages). Noise was explicitly stated as one of the explanatory factors for the fatal outcome in 2.2% (17/788) of the fatal accidents, particularly when the work involved vehicular movement or the need to communicate between workers. Noise was not typically considered a unique cause in the accident, notably because the investigators considered that the accident would have probably occurred due to other risk factors (for example, disregard of safety rules, shortcomings in work methods, and inadequate training). Noise is an important risk factor when communication is involved in work. Since noise is ubiquitous and may also interfere with vigilance and other risk factors for accidents, it may be a much more important contributing factor to accidents than is currently recognized.

Dose - response relationship between noise exposure and the risk of occupational injury

Many workers worldwide experience fatality and disability caused by occupational injuries. This study examined the relationship between noise exposure and occupational injuries at factories in Korea. A total of 1790 factories located in northern Gyeonggi Province, Korea was evaluated. The time-weighted average levels of dust and noise exposure were taken from Workplace Exposure Assessment data. Apart occupational injuries, sports events, traffic accidents, and other accidents occurring outside workplaces were excluded. The incidences of occupational injury in each factory were calculated by data from the Korea Workers' Compensation and Welfare Services. Workplaces were classified according to the incidence of any occupational injuries (incident or nonincident workplaces, respectively). Workplace dust exposure was classified as <1 or ≥ 1 mg/m³ , and noise exposure as <80, 80-89, or >90 dB. Workplaces with high noise exposure were significantly associated with being incident workplaces, whereas workplaces with high dust exposure were not. The odds ratios (95% confidence intervals) derived from a logistic regression model were 1.68 (1.27-2.24) and 3.42 (2.26-5.17) at 80-89 dB and ≥ 90 dB versus <80 dB. These associations remained significant when in a separate analysis according to high or low dust exposure level. Noise exposure increases the risk of occupational injury in the workplace. Furthermore, the risk of occupational injury increases with noise exposure level in a dose-response relationship. Therefore, strategies for reducing noise exposure level are required to decrease the risk of occupational injury.

Occupational noise exposure and noise-induced hearing loss are associated with work-related injuries leading to admission to hospital

OBJECTIVE

This study focuses on work-related injuries that required admission to hospital in a population of male workers exposed to occupational noise (≥80 dBA) which some displayed a hearing loss due to their exposure.

METHODS

The study population count 46 550 male workers, 1670 (3.6%) of whom incurred at least one work-related injury requiring admission to hospital within a period of 5 years following hearing tests conducted between 1987 and 2005. The noise exposure and hearing loss-related data were gathered during occupational noise-induced hearing loss (NIHL) screening. The hospital data were used to identify all members of the study population who were admitted, and the reason for admission. Finally, access to the death-related data made it possible to identify participants who died during the course of the study. Cox proportional hazards model taking into account hearing status, noise levels, age and cumulative duration of noise exposure at the time of the hearing test established the risk of work-related injuries leading to admission to hospital.

RESULTS

For each dB of hearing loss, a statistically significant risk increase was observed (HR=1.01 dB 95% CI 1.006 to 1.01). An association (HR=2.36 95% CI 2.01 to 2.77) was also found between working in an occupational ambient noise ≥100 dBA and the risk of injury.

CONCLUSIONS

From a safety perspective, this issue is highly relevant; especially when workers are exposed to intense ambient noise and NIHL.

O espectro da neuropatia auditiva pode contribuir para acidente de trabalho? o relato de uma investigação clínica

Considerando a possível insuficiência do exame admissional legalmente preconizado para avaliação auditiva no que se refere à identificação de comprometimento da habilidade para reconhecer fala em ambiente ruidoso, este trabalho tem como objetivo relatar o processo de uma investigação clínica, conduzida em 2010, de um trabalhador que sofreu acidente de trabalho, visando identificar possíveis elementos clínicos não previamente considerados, mas que poderiam ter contribuído para a ocorrência do acidente. Utilizou-se a escala Abbreviated Profile of Hearing Aid Benefit para comparar a habilidade de reconhecimento da fala em ambiente ruidoso do trabalhador acidentado com a de ouvintes normais e realizaram-se exames de audiometria, imitanciometria, emissões otoacústicas, potencial evocado auditivo de tronco encefálico e teste de reconhecimento de sentenças no silêncio e no ruído. Identificou-se que o trabalhador apresentava espectro da neuropatia auditiva (ENA) e que a alteração neural prejudicava de forma relevante a compreensão da fala em presença de ruído. A avaliação da sensibilidade auditiva no exame admissional se mostrou insuficiente para identificar a real situação auditiva do trabalhador com ENA, que compromete o reconhecimento de sinais de advertência, levando a um aumento no risco de ocorrência de acidente em ambientes ruidosos.