Preventing Occupational Hearing Loss

Hearing Conservation Procedure

Occupational exposure to noise is a significant health risk and can lead to hearing loss. Under current OSHA standards, any employee whose 8-hour TWA exceeds 85 dBA is required to be enrolled in a hearing conservation program.

This program prevents initial occupational hearing loss and protects remaining hearing by reducing both exposure time and intensity. It also provides annual training and audiometric testing.


All employees enrolled in the Hearing Conservation Program must be given a baseline audiogram. Annual follow up audiograms are compared to the initial test results to detect standard threshold shifts which may signal the need for further protective measures. Training is provided to help employees recognize the importance of protecting their hearing and to learn how to properly wear personal protective equipment. Training is also available to those supervisors who oversee the work areas requiring high noise levels. Supervisors are encouraged to notify EHRS of any process, materials or equipment changes that may impact noise exposures.

Federal OSHA requirements dictate that whenever employee 8-hour time weighted average (TWA) sound levels exceed 85 decibels, a continuing effective hearing conservation program must be instituted. In addition to training, engineering and administrative control methods must be investigated, evaluated and, where feasible, utilized to reduce exposures. In the event that these controls do not reduce exposures to below 85 decibels, personal protective equipment must be supplied and used.


Hearing loss is one of the most common work-related illnesses. It is also completely preventable, and the good news is that it can be prevented by regularly using hearing protection while exposed to hazardous noise levels.

MIT EHS Industrial Hygiene Program has developed a SOP (Standard Operating Procedure) for Hearing Conservation that can be found under Forms/SOP (keyword search: hearing, noise, audiogram).

The Occupational Safety and Health Administration requires that whenever the noise level at any facility exceeds an action level of 85 decibels averaged over an eight-hour time weighted average, a hearing conservation program must be initiated. These programs must include monitoring of employee exposure to noise, identification of employees who are exposed to these levels and annual audiometric testing.

The challenge for many HCPs is how to evaluate the effectiveness of their programs. There is no consensus on a method for measuring HCP effectiveness, and only limited research has been conducted in this area.


In addition to performing pure tone air conduction audiometric testing, the certified occupational hearing conservationist may also be responsible for fitting workers with custom or pre-molded ear plugs or other personal protective devices. They can also assist with education, training and enforcing hearing conservation program compliance.

OSHA requires employers to establish a hearing conservation program for employees when their noise exposure levels exceed 80 decibels averaged over an 8-hour time-weighted average (TWA). Noise monitoring is performed using both area and personal dosimetry. If the exposure level is successfully reduced below 80 dBA after implementation of engineering controls, then the employee will be de-enrolled in the HCP.

Educating employees is critical in this process. In addition to explaining the importance of protecting their hearing, it is important to emphasize that NIHL is fully preventable. This is especially true for children, who are exposed to firearms, music, power tools and loud toys on a regular basis that can increase their risk of NIHL.


Repeated unprotected exposure to hazardous noise can cause hearing loss over a long period of time. It is difficult to reverse and can only be prevented by using engineering controls, administrative controls and hearing protection.

Annual audiometric testing is performed for employees with a Time Weighted Average exposure that exceeds 85 dBA (8 hour TWA). This yearly test serves two purposes: 1) it helps to identify individuals who have experienced a threshold shift that may indicate the need for further preventive measures; and, 2) it provides information concerning the effectiveness of the program.

Employees will be provided with personal hearing protectors (ear plugs or muffs) and be shown how to fit them correctly in order to maximize comfort and noise reduction. The type of protectors provided will be based on the sound levels in the work area where employees are expected to be exposed.

Records and documentation of the hearing conservation program will be maintained as specified in the OSHA standard. These records will be made available to affected employees, their representatives and the assistant secretary of labor upon request.

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