Home » Business Division » Manufacturing » News and Events

News and Events  

Manufacturing Risk Advisor – NIHL - October 2018

Noise is a significant occupational disease exposure

Noise-induced hearing loss (NIHL) is widespread and irreversible. Intense noise can lead to an increased number of accidents, reduced work efficiency, and can lead to other physiological and psychological problems. Environmental factors such as duration of time spent in the noisy environment and presence of impulsive noise influence whether an individual will suffer from NIHL. In the early stages of noise exposure, a worker may have trouble hearing when moving from the noisy environment to a quiet area. Usually, hearing will return to normal within several minutes. This is often referred to as a temporary threshold shift (TTS). A noise capable of causing TTS from a brief exposure can lead to permanent hearing loss with prolonged or recurrent exposures. This is called a permanent threshold shift (PTS) and ringing of the ears after working in noisy environments is an early sign of this type of hearing loss. As of now, there is no way to reverse permanent NIHL that results from noise exposure.

Can NIHL be avoided?

Noise-induced hearing loss (NIHL) can be prevented at any age using proper controls. The Hierarchy of Controls can be used to determine how to implement feasible and effective controls. This approach prioritizes controls by their likely effectiveness in reducing or removing the noise hazard. The most effective approach is to eliminate the noise source, or substitute the noisy process or equipment for a quieter option. If neither of those options is feasible, the combination of engineering and administrative controls should be used. Engineering controls can include redesigning the equipment or adding barriers to prevent noise from reaching workers. Administrative controls can include having workers on a rotational schedule to reduce excessive noise exposure or providing quiet break areas. When all options for eliminating or reducing noise are exhausted, hearing protection devices should be made available to workers at no cost. The goal of all these controls is to attenuate noise exposure to below 85 dBA as an 8-hour time weighted average.


• Occupational hearing loss is one of the most common work-related illnesses in the United States.

• Hearing loss can occur over a long period of time or instantly.


Refer to Liberty Mutual reference notes OSHA Hearing Conservation Program, RC 5547; Hearing Conservation OSHA 29 CFR 1910.95, RC 4504; and Hearing Protection: A Guide for Supervisors, RC 5055, available on Liberty Mutual SafetyNet™.

1. National Institute on Deafness and Other Communication Disorders. (2017, February 08). U.S. adults aged 20 to 69 years show signs of noise-induced hearing loss. Retrieved from https://www.nidcd.nih.gov/

2. Liberty Mutual Insurance. (2014). Noise, RC 6103. Retrieved from Liberty Mutual SafetyNet™.

3. The National Institute for Occupational Safety and Health. (2016, November 10). Noise and hearing loss prevention: Hierarchy of controls. Retrieved from https://www.cdc.gov/