The Effect of Fitting the Right Hearing Protection Device: An Intervention Study

Abstract

Background: It is estimated that noise-induced hearing loss (NIHL) affects almost 2% of the New Zealand workforce. There is no cure for NIHL, thus, prevention is imperative. Occupational noise reaches dangerous levels in the workplace and along with macro occupational noise management, personal hearing protection devices (HPD) may be required. Poor selection of HPD can lead to the removal of the device. This may be due to overprotection, comfort issues or an unsuitable style. Furthermore, lack of training on HPD fitting technique can lead to poor attenuation of HPDs. Aims: The purpose of this study was to measure the noise levels within three factories through sound-level measurement and noise dosimetry, and assess the employees’ workday to recommend the correct class of hearing protection devices (HPDs). It then looked to investigate the effects of an intervention where employees selected their own HPDs from a range of options and were trained how to use it. Methods: Noise-maps were created through sound-level measurements and noise dosimetry. The employers provided information on their current methods of HPD provision processes. Factory employees completed a questionnaire to assess the use and any barriers to the use of their current HPDs. The questionnaire also assessed employee hearing protection device behaviours, attitudes and knowledge about hearing loss. After a recommendation of HPD was provided for each employee, the workers were given the style of their choice and taught how to fit it. The questionnaire was also provided one-week and two-months after the intervention. Results: Findings showed a marginally significant increase in the supports-to-barriers ratio one week following the intervention and a further increase at the two-month point. Knowledge and attitudes towards hearing loss and noise did not change over time. There was a slight increase in hearing protection device behaviour following the intervention and this was maintained two months later. Conclusion: The most protection does not indicate optimal protection in the selection of HPD devices and employers need to be informed on how overprotection can lead to poor HPD self-reported behaviours. High peak level noise is detrimental to overprotection and should be investigated. Furthermore, there is a lack of lower class HPD styles on the market, affecting the implementation of selection intervention programmes. Training contributed to the increase in the supports-to-barriers ratio, as this support specifically increased following the intervention. Evidence-based selection and training programmes are important to improve supports, and decrease barriers to HPD use in the workplace.