OSHA Occupational Noise Exposure Standard: Protecting Workers' Hearing

Noise is unwanted sound and is an extensive occupational health problem. More than 30 million Americans are exposed to hazardous sound levels on a regular basis. Unlike many occupational hazards, exposures to harmful sound levels can also occur in recreational settings, homes, almost anywhere. Thus, the effects of a work exposure may be aggravated by other activities. To protect hearing, people should take measures to limit or minimize all exposures to harmful sound levels.

OSHA regulates workplace noise because prolonged exposure to loud machinery can damage the delicate hair cells in the inner ear, leading to permanent hearing loss and chronic ringing. Its legal muscle is 29 CFR 1910.95, which caps an eight-hour shift at 90 dBA and says employers must start a hearing-conservation program once exposures hit 85 dBA. The rule most affects workers in construction, manufacturing, aviation, and transportation, where noise levels often exceed OSHA limits.

The Occupational Noise Exposure Standard requires that protection against the effects of noise exposure be provided when sound levels exceed those shown in Table G-16 when measured on the A scale of a standard sound level meter at slow response.

If these controls fail to reduce the sound level to those listed, personal protective equipment must be provided and used to reduce sound levels to within the levels of the table. You can see how this plays out on the chart above. What does this look like in real life?

Hearing loss occurs in two basic ways:

Conductive hearing loss is caused by a problem with a part of the outer or middle ear. A breakdown or obstruction interferes with sound transmission. This type of hearing loss is common and can often be reversed and hearing restored with appropriate treatment.
Sensorineural hearing loss occurs from changes in the receptor hair cells in the inner ear or in the nerves carrying impulses to the brain. This type of hearing loss is usually permanent.

Noise-induced hearing loss (NIHL) is sensorineural and is usually permanent.

Worried about noise exposure on the job? You're not alone. Work is one of the most common places you can be exposed to harmful levels of noise, which puts you at risk of noise-induced hearing loss (NIHL). Fortunately, the US Occupational Safety and Hazard Administration (OSHA) has standards and programs aimed at reducing the risk of hearing loss among American workers. This does not mean you have to be exposed to eight continuous hours of loud sound to qualify for help with noise exposure.

Key OSHA Definitions

OSHA defines specific limits for occupational noise exposure to protect workers’ hearing.

Permissible Exposure Limit (PEL): Under the OSHA noise standard, the permissible exposure limit is 90 dBA averaged over an eight-hour workday.
Action Level: An action level of 85 dBA TWA compels employers to launch a hearing-conservation program.
5-dB Exchange Rate: The OSHA noise standard also relies on a 5-dB exchange rate.
Peak Sound Pressure Limit: For impulsive or impact sounds, OSHA sets an absolute peak cap of 140 dB.

Understanding OSHA's Noise Exposure Limits

Noise Exposure Monitoring

The PEOSH Occupational Noise Exposure Standard, 29 CFR1910.95, states that “When information indicates that any employee’s exposure may equal or exceed an 8-hour time-weighted average of 85 decibels (dB) the employer shall develop and implement a monitoring program (29 CFR 1910.95(d)).” The noise levels in a work place should be carefully monitored using the correct grade of equipment if there is any possibility that a worker will be exposed and an 8 hour time weighted average noise level of 85 dB(A) or above. This monitoring should be repeated periodically (e.g.

Methods of Noise Monitoring

The three most common methods of noise monitoring are:

Area surveys
Personal dosimetry
Engineering surveys

In an area survey, a sound level meter is used to measure environmental noise levels. This information may be used to identify areas where more thorough noise exposure evaluation is needed. Personal dosimetry, a method of evaluating an employee’s individual exposure, is used to determine the noise levels experienced by employees throughout the work shift. A noise measuring instrument with the microphone positioned in the employee’s hearing zone is used to measure sound levels. OSHA defines the “hearing zone” as a two-foot sphere around the employee’s head. This type of monitoring result can also represent the exposure of other workers whose exposures result from the same tasks.

During engineering surveys, octave band analyzers and sound level recorders are used to obtain information on the frequency/intensity composition of noise.

How is Noise Measured?

Basically, there are two different instruments to measure noise exposures: the sound level meter and the dosimeter.

A sound level meter is a device that measures the intensity of sound at a given moment. Since sound level meters provide a measure of sound intensity at only one point in time, it is generally necessary to take a number of measurements at different times during the day to estimate noise exposure over a workday. To estimate employee noise exposures with a sound level meter it is also generally necessary to take several measurements at different locations within the workplace. After appropriate sound level meter readings are obtained, people sometimes draw “maps” of the sound levels within different areas of the workplace. By using a sound level “map” and information on employee locations throughout the day, estimates of individual exposure levels can be developed.
A dosimeter is like a sound level meter except that it stores sound level measurements and integrates these measurements over time, providing an average noise exposure reading for a given period of time, such as an 8-hour workday. With a dosimeter, a microphone is attached to the employee's clothing and the exposure measurement is simply read at the end of the desired time period. A reader may be used to read-out the dosimeter's measurements. Since the dosimeter is worn by the employee, it measures noise levels in those locations in which the employee travels. A sound level meter can also be positioned within the immediate vicinity of the exposed worker to obtain an individual exposure estimate.

Area monitoring can be used to estimate noise exposure when the noise levels are relatively constant and employees are not mobile. In situations where personal monitoring is appropriate, proper positioning of the microphone is necessary to obtain accurate measurements. With a dosimeter, the microphone is generally located on the shoulder and remains in that position for the entire workday. Manufacturer's instructions, contained in dosimeter and sound level meter operating manuals, should be followed for calibration and maintenance.

To be sure of getting accurate and repeatable noise measurements that can be used for protecting workers' hearing and protecting your company from legal claims, you should use the correct grade of sound level meter. The OSHA regulations recommend the use of a Type 2 sound level meter (you can also use Type 1 as it is more accurate) with "Slow" time weighting. You should also use a Sound Level Calibrator to check that the meter is operating correctly before making important measurements.

When is it Necessary to Implement a Noise Monitoring Program?

It is not necessary for every employer to measure workplace noise. Noise monitoring or measuring must be conducted only when exposures are at or above 85 dB. Factors which suggest that noise exposures in the workplace may be at this level include employee complaints about the loudness of noise, indications that employees are losing their hearing, or noisy conditions which make normal conversation difficult. The employer should also consider any information available regarding noise emitted from specific machines.

The amendment requires that when there are significant changes in machinery or production processes that may result in increased noise levels, remonitoring must be conducted to determine whether additional employees need to be included in the hearing conservation program.

Where Can Equipment and Technical Advice be Obtained?

Noise monitoring equipment may be either purchased or rented. Sound level meters cost about $500 to $1,000, while dosimeters range in price from about $750 to $1,500. Smaller companies may find it more economical to rent equipment rather than to purchase it. Names of equipment suppliers may be found in the telephone book (Yellow Pages) under headings such as: “Safety Equipment,” “Industrial Hygiene,” or “Engineers-Acoustical.” In addition to providing information on obtaining noise monitoring equipment, many companies and individuals included under such listings can provide professional advice on how to conduct a valid noise monitoring program. Some audiological testing firms and industrial hygiene firms also provide noise monitoring services.

Free, on-site assistance may be obtained from OSHA-supported state and private consultation organizations.

Hearing Conservation Program

Once employee noise exposure reaches the 85 dBA action level, OSHA requires employers to implement a hearing conservation program.

The employer shall administer a continuing, effective hearing conservation program, as described in paragraphs (c) through (o) of this section, whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent.

Audiometric Evaluation

Audiometric evaluation is required if employees are exposed to sound levels equal to or exceeding an 8 hour TWA of 85 dB. This evaluation consists of a baseline audiogram obtained within 6 months of an employee’s first exposure to levels of 85dB or greater followed by yearly retesting. The baseline audiogram must be preceded by 14 hours without exposure to workplace noise.

Within six months of employment in an environment where they are exposed to loud noises, employees must be given a baseline audiogram. Thereafter, they should be provided with a yearly audiogram by a certified audiologist, free-of-charge.

The baseline audiogram is then compared to the most recent test to determine if the audiogram is valid and if a standard threshold shift (STS) has occurred in the employee’s hearing. A STS is defined as an average shift from baseline of 10 dB or more in the audiometric frequencies 2000, 3000, and 4000 Hz. In determining whether a STS has occurred an adjustment allowing for the contribution of aging (presbycusis) to hearing loss may be made. The procedure for this adjustment is described in Appendix F of the standard (Calculation and Application of Age Correction to Audiograms).

A STS is a sign that the employee has begun to lose hearing and that intervention is needed to prevent further hearing loss. If an STS has occurred, the employer must notify the affected employee in writing within 21 days.

Audiometric Testing Program

Audiometric tests shall be performed by a licensed or certified audiologist, otolaryngologist, or other physician, or by a technician who is certified by the Council of Accreditation in Occupational Hearing Conservation, or who has satisfactorily demonstrated competence in administering audiometric examinations, obtaining valid audiograms, and properly using, maintaining and checking calibration and proper functioning of the audiometers being used. A technician who operates microprocessor audiometers does not need to be certified.
Where mobile test vans are used to meet the audiometric testing obligation, the employer shall obtain a valid baseline audiogram within 1 year of an employee's first exposure at or above the action level.
Testing to establish a baseline audiogram shall be preceded by at least 14 hours without exposure to workplace noise.

Audiometric Test Requirements

Audiometric tests shall be pure tone, air conduction, hearing threshold examinations, with test frequencies including as a minimum 500, 1000, 2000, 3000, 4000, and 6000 Hz.
The functional operation of the audiometer shall be checked before each day's use by testing a person with known, stable hearing thresholds, and by listening to the audiometer's output to make sure that the output is free from distorted or unwanted sounds.
Audiometer calibration shall be checked acoustically at least annually in accordance with appendix E: Acoustic Calibration of Audiometers. Test frequencies below 500 Hz and above 6000 Hz may be omitted from this check.
An exhaustive calibration shall be performed at least every two years in accordance with sections 4.1.2; 4.1.3.; 4.1.4.3; 4.2; 4.4.1; 4.4.2; 4.4.3; and 4.5 of the American National Standard Specification for Audiometers, S3.6-1969.

Administrative and Engineering Controls

To reduce workplace noise exposure, OSHA emphasizes following the hierarchy of controls-prioritizing long-term solutions over temporary fixes.

Administrative and engineering controls can be used to reduce exposures to the point where the hazard is eliminated or reduced to manageable proportions. These control measures consist of removing the worker or removing the hazard. This may be accomplished by substituting less noisy equipment for instance. Administrative controls include work scheduling and task assignment. Individual employee exposure is reduced by decreasing the amount of time spent in a noisy environment. Engineering controls include mufflers, sound barriers, enclosures, and sound absorbing materials.

Another way to reduce noise is to use administrative controls. This means employers makes adjustments to the work schedule or workplace that don't require much physical modification.

Hearing Protection

Personal protective equipment for hearing protection is of two basic types, ear plugs and muffs, and a variety of each type is available. The choice of hearing protection provided should be based on the sound levels present in the workplace where the hearing protection will be used.

Employers shall make hearing protectors available to all employees exposed to an 8-hour time-weighted average of 85 decibels or greater at no cost to the employees.
The employer shall evaluate hearing protector attenuation for the specific noise environments in which the protector will be used.
The adequacy of hearing protector attenuation shall be re-evaluated whenever employee noise exposures increase to the extent that the hearing protectors provided may no longer provide adequate attenuation.

Noise-canceling headphones are great for blocking out ambient noise when you're listening to music or a podcast.

Noise Reduction Rating (NRR)

The Noise Reduction Rating (NRR) is a single-number rating method that describes the protection provided by a hearing protector. It indicates how much the overall noise level is reduced by the hearing protector. Field studies by the National Institute for Occupational Safety and Health (NIOSH) have shown that employees normally achieve only about 1/2 of the noise reduction provided by hearing protection. To correctly estimate the noise reduction provided by hearing protection devices, it is important to remember to first subtract 7 from the NRR and then subtract the remainder from the A weighted noise level.

Training Program

The employer shall train each employee who is exposed to noise at or above an 8-hour time weighted average of 85 decibels in accordance with the requirements of this section.
The training program shall be repeated annually for each employee included in the hearing conservation program.

Access to Information and Training Materials

Exposure measurements.
Audiometric tests.

Record Retention

Access to records. All records required by this section shall be provided upon request to employees, former employees, representatives designated by the individual employee, and the Assistant Secretary.
Transfer of records.

OSHA Resources

Employee exposure to occupational noise hazards is addressed in OSHA’s general industry standards and the recording of occupational hearing loss is addressed in OSHA’s injury and illness recordkeeping regulation. This section highlights OSHA standards/regulations and documents related to noise.

Section 5(a)(1) of the OSH Act, often referred to as the General Duty Clause, requires employers to "furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees". This section may be used to address hazards for which there are no specific OSHA standards, e.g.

There are 29 OSHA-approved State Plans operating state-wide occupational safety and health programs.

Other Resources

Note: These are NOT OSHA standards or regulations. However, they do provide guidance from their originating organizations related to worker protection from noise.

49 CFR 227, Occupational Noise Exposure for Railroad Operating Employees. Requires railroads to monitor noise exposures and implement a hearing conservation program for employees whose exposure to cab noise equals or exceeds an 8-hour TWA of 85 dBA.
Occupational Noise Exposure. Publication No. 98-126, (June 1998). Includes revisions to previous 1972 recommendations that go beyond attempting to conserve hearing by focusing on preventing occupational noise-induced hearing loss.
Recommendations on Control of Excessive Noise. Navigation and Vessel Inspection Circular No.
DoD Hearing Conservation Program. Instruction No. 6055.12 (August 14, 2019).
Navy Medicine Hearing Conservation Program Technical Manual. NMCPHC TM-6260.51.99-3 (July 2020).
Hearing Center of Excellence. Defense Health Agency, Military Health System.

ANSI Standards

Note: These are NOT OSHA standards or regulations.

S3.1, Maximum Permissible Ambient Noise Levels for Audiometric Test Rooms.
S3.6, American National Standard Specification for Audiometers.
S12.6, Methods for Measuring the Real-Ear Attenuation of Hearing Protectors.
S12.71, Performance Criteria for Systems that Estimate the Attenuation of Passive Hearing Protectors for Individual Users.
S1.4, American National Standard Specification for Sound Level Meters.
S1.25, American National Standard Specification for Personal Noise Dosimeters.

Protecting Your Hearing

Regardless, it is always a good idea to protect your hearing from harmful noise, whether at work and at home. You might be wondering how loud is too loud? Unfortunately, not all worksite sound is predictable or easily measurable. harmful. Sudden blasts at a worksite, for example, may only last seconds but cause severe hearing damage. Or you may not have thought your environment was loud initially, but after awhile you begin to experience symptoms like muffled hearing or ringing in the ears.

Workers have the right to a safe workplace and freedom from being affected by noises loud enough to induce hearing loss. In many situations, workers can file for workers' compensation benefits if they believe their hearing has been damaged on the job. It's important to know you have resources if your employer is not doing enough to protect workers' hearing.

OSHA provides a wealth information for workers on their site. They also provide specific guidance on what to do if you're being exposed to any harmful activities, not just noise. If you've noticed changes to your hearing or are experiencing tinnitus following exposure to loud noise, it's important to get evaluated by a hearing specialist in your area.