Hearing Loss Prevention

Supervisor responsibilities

• Implementing engineering and/or administrative controls to reduce noise exposure.
• Notifying Environmental Health & Safety of changes in work processes or equipment which affect noise levels.
• Notifying Environmental Health & Safety of employee new hires, rehires, transfers, or terminations.
• Ensuring that proper hearing protection is provided.
• Enforcing the use of required hearing protection.
• Assuring employees attend required HLP training.

Employee responsibilities

• Following safe work practices that reduce or prevent occupational noise exposures.
• Attending HLP required training.
• Participating in the audiometric testing under the Occupational Health Assurance Program.
• Wearing properly fitted hearing protection when necessary.
• Reporting to supervisors any changes in processes or equipment that alter noise levels.

Environmental Health & Safety

• Prioritizing evaluations of work areas based on noise exposure.
• Performing noise measurements.
• Educating supervisors and employees about the effects of noise.
• Consulting and advising on engineering and administrative controls to reduce noise exposure.
• Recommending proper hearing protection devices.
• Providing annual hearing test services under the Occupational Health Assurance Program.
• Training employees and supervisors in the need for, and proper use and care of hearing protection devices.

Hearing Loss Prevention (HLP) is a systematic approach to evaluate workplace noise levels. The first step is to anticipate that noise levels generated while using certain equipment may be a concern. Chainsaws, masonry drills, tractors, and mowers, for example, are known to generate high noise levels when in use. Employees operating such equipment can have potentially high noise exposures and should be enrolled in the hearing conservation program. 

Noise monitoring will be conducted when exposures may be at or above 85 dBA. Factors that 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 where employees have to shout to communicate with each other at a distance of three feet. Another indicator is if, after being exposed to high noise levels on the job, employees notice that speech and other sounds are muffled for several hours or they develop ringing in their ears. Where noise exposures for a person are highly variable because the tasks and equipment used change frequently but where there are noise exposures of concern, it may not be possible to do noise monitoring that is meaningful; under those conditions, it is recommended the employee use hearing protection and be enrolled in the hearing conservation program.

It is the responsibility of supervisors to notify Environmental Health & Safety if questionable noise levels are being generated by equipment or processes by calling 540-231-3600.

The preferred method of controlling excessive exposure to noise sources is by using engineering controls wherever feasible. While performing a noise survey, Environmental Health & Safety works with the supervisor and employees to identify the dominant noise source(s) in an area.

The OSHA Occupational Noise Exposure Standard (1983) 1910.95 requires that employees be protected against effects of noise exposure when sound levels exceed the table below when measured with a sound level meter set on the dBA scale at slow response.

If noise exposure concerns are identified, feasible administrative (i.e., worker-machine rotation, breaks from noise) or engineering (i.e. quieter machinery, noise path absorbers or barriers, mufflers, isolation) controls must be utilized. If such controls fail to reduce sound levels to within the acceptable levels, personal protective equipment (i.e., earplugs, earmuffs) must be provided and used. 

Excessive noise exposures may be reduced by controlling the noise emitted at the source, along the path, or at the receiver (employee). The method chosen is dependent upon the particular problem to be solved and is limited by such factors as feasibility, relative effectiveness, and impact upon the employees and their productivity.

Administrative controls include a very broad and often practical range of noise control solutions. The most common administrative noise control is the modification of work schedules to limit employee noise exposures. This can not only reduce noise exposures but can sometimes increase productivity by dividing a demanding task between two or more employees. Caution must be taken to prevent an increase in the percentage of the workforce being exposed to noise hazards. A regularly scheduled equipment maintenance program and the establishment of set noise control limits for new or modified equipment are also effective administrative means of controlling noise and will be highly recommended to affected work areas and supervisors.

It is the policy of OSHA to enforce the use of engineering and administrative noise controls wherever feasible, particularly in areas where hearing protection devices alone are not adequate. Environmental Health & Safety will provide recommendations on engineering or administrative controls, but the implementation of these controls is the responsibility of the department.

Audiometric testing is an integral part of the Hearing Loss Prevention Program because it is the only true measure of the program's effectiveness in preventing occupational noise-induced permanent hearing loss. The purpose of the tests will be to identify workers in the early stages of hearing loss and allow intervention before the loss becomes worse.

The Occupational Health Assurance Program provides annual audiometric testing at no cost for employees who are known to work in areas with high-level noise exposures (TWAs of 85 dBA or greater). Audiometric testing will be scheduled by the Environmental Health & Safety medical services coordinator with the exposed employee's supervisor. On-campus clients have audiograms conducted at Environmental Health & Safety and off-campus clients have audiograms provided through contracted mobile testing services and/or local medical services providers.

Each employee receives a confidential copy of the audiometric testing results. Audiometric data records will be retained for the duration of employment plus 30 years.

A baseline audiogram is the audiogram against which future audiograms are compared. Baseline audiograms are provided within 6 months (or within 1 year for mobile van testing) of noise exposure. It is crucial for employees to avoid noise exposures for 14 hours before the baseline test. The regulation permits hearing protection to be substituted if you cannot avoid workplace noise. However, hearing protection must be of the appropriate type and properly worn to be effective. Since the new employee has not been formally fitted and trained to use hearing protection, avoiding noise exposure is preferred.

Employees enrolled in the HCP will have another audiogram annually. Each employee's annual audiogram is compared to that employee's baseline audiogram to determine if the audiogram is valid and if a standard threshold shift has occurred.

The results of audiometric testing will be used to determine if and what type of hearing protection is needed, and if already in use, what further steps must be taken to control an excessive noise exposure problem.

If the annual audiogram shows that an employee has suffered a standard threshold shift, then the employee is retested. If the STS is confirmed, then the audiologist determines if a referral for clinical audiological or otological (ear) examination is recommended. Each employee is notified in writing with 21 days of this determination.

Unless a physician determines that the STS is not work related or aggravated by occupational noise exposure, then the following steps are taken:  

1. Employees not using hearing protectors will be fitted with hearing protectors, trained in their use and care, and required to use them.
2. Employees already using hearing protectors will be refitted and retrained in the use of hearing protectors and provided with hearing protectors offering greater attenuation if necessary.
3. The employee will be referred for a clinical audiological evaluation or an otological examination, as appropriate, if additional testing is necessary or if it is suspected that a medical pathology of the ear is caused or aggravated by the wearing of hearing protectors.
4. The employee is informed of the need for an otological examination if a medical pathology of the ear that is unrelated to the use of hearing protectors is suspected.

Engineering and administrative controls are the most effective and preferred methods to prevent noise-induced hearing loss. In many cases, however, prevention methods also include the use of Hearing Protection Devices (HPDs). These simple and inexpensive devices can prevent noise-induced hearing loss, but as with all types of personal protective equipment, their effectiveness depends upon proper:

• Selection
• Fitting
• Education
• Proper and consistent uses when exposed to noise

Environmental Health & Safety recommends appropriate HPDs based on noise attenuation requirements. A variety of appropriate types of protectors must be made available to employees. The employee's department must pay for and continue to provide any required HPD to the employee at no cost. Employees are responsible for wearing required HPD and supervisors are responsible for enforcing consistent HPD use.

The two most commonly used types of HPDs at Virginia Tech are earplugs and earmuffs. An ear plug is inserted into the ear canal to reduce the amount of noise that reaches the ear via that route. An earmuff is worn over the ear to reduce the amount of noise the ear receives via the ear canal. These HPDs can not eliminate all the noise reaching the ear as noise can take many routes into the ear.

To prevent noise-induced hearing loss, HPDs must reduce noise exposure to time-weighted average levels of 90 dBA or below, or to 85 dBA or below for those workers who have suffered a standard threshold shift.

An earplug or earmuff is designed to reduce noise exposure by a certain amount. These are also called Hearing Protection Devices (HPDs). However, the best HPD for employees is removing the hazardous noise. Until that happens though, the best hearing protection is one the employee will wear willingly and consistently. 

Here are some issues of employee acceptance and use of HPDs:

• Convenience and availability;
• Confidence that the HPD can be worn correctly;
• Confidence that the HPD will prevent hearing loss;
• Confidence that the HPD will not impair the ability to hear important sounds;
• Comfort and ease of fit; and/or
• Compatibility with other personal protective equipment.

Employees exposed to noise levels of 85 dBA TWA or higher are required to attend Hearing Loss Prevention Training annually. Supervisors shall ensure that employees attend the required training.

The content of the training includes:

• The effects of noise on hearing;
• The purpose of hearing protection devices (HPDs);
• The advantages, disadvantages, and attenuation of various HPDs;
• Instructions on HPD selection, fitting, use, and care;
• The purpose of audiometric testing; and
• An explanation of the audiometric test procedures.

The Virginia Tech HLP includes detailed and accurate recordkeeping as required by OSHA. Environmental Health & Safety will maintain a record of all employee exposure measurements. Detailed audiometric records will be kept to determine whether a worker has incurred a significant threshold shift, or whether thresholds are decreasing gradually over time. Both present and former employees, or representatives designated by the employee, will be provided their audiometric and monitoring records upon written request.

Action level: The noise level (85 dBA), calculated as an eight-hour, time-weighted average, at which OSHA requires exposed employees to be included in the Hearing Loss Prevention Program.

Administrative controls: When OSHA PEL exposure levels are exceeded, feasible administrative (i.e. worker-machine rotation, breaks from noise) or engineering controls shall be utilized. If administrative or engineering controls fail to reduce sound levels within OSHA PEL exposure levels, personal hearing protective devices shall be provided to the employee by the employer and used to reduce sound levels to within the levels of OSHA PEL exposure levels.

Attenuation: The reduction in sound pressure level in dB which occurs as a person moves further and further away from a noise source (i.e. moving out-of-doors or down an air-conditioning duct system).

Audiogram: The chart, graph, or table showing hearing threshold level as a function of frequency; a method of measuring the degree of hearing loss.

Audiologist: A professional, specializing in the study and rehabilitation of hearing, who is certified by the American Speech-Language-Hearing Association or licensed by a state board of examiners.

Audiometry: A baseline audiogram must be obtained for each employee at the beginning of employment or within 6 months of the first noise exposure. An annual audiogram is required thereafter.

Baseline audiogram: The audiogram against which future audiograms are compared.

CFR: Code of Federal Regulation.

Continuous noise: The type of constant, unchanging noise which is generated by turbines, air conditioners, or fans.

Criterion sound level: The dB level at which permissible exposure level is reached; for OSHA, the criterion is 90 dBA (which will result in a maximum dose of 100%).

dB(A): The unit of measurement of sound level in dB using a weighting network of the A scale on a SLM. A-weighting is a pitch/frequency response filter adjustment that makes its reading conform, very roughly, to the human ear response at a loudness level of 40 phons.

dB(B): The unit of measurement of sound level in dB using a weighting network of the B scale on a SLM. B-weighting is a pitch/frequency response filter adjustment that simulates the human ear response at a loudness level of 70 phons.

dB(C): The unit of measurement of sound level in dB of the C scale on a SLM. In this case, the SLM reading contains no weighting network in the circuit (i.e. it is flat).

Decibel (dB): The unit of measurement of sound level.

Dose: The percentage representation of exposure level, based on an 8 -hour criterion.

Dosimeter: A special battery-powered sound level meter that is worn by the worker being monitored for noise exposure. It continuously computes TWA and noise dose using a specified exchange rate for trading sound level and exposure duration. The rate for OSHA is 5 dB increase per halving of time.

Engineering controls: When OSHA PEL exposures are exceeded, feasible engineering controls (i.e. quieter machinery, noise path absorbers or barriers, mufflers, or equipment isolation) or administrative controls shall be utilized. If such controls fail to reduce sound levels within OSHA PEL exposure limits, personal hearing protective equipment shall be provided to the employee by the employer and used to reduce sound levels to within OSHA PEL limits. The preferred method of noise control is engineering to reduce the noise at its source by engineering controls.

Exchange or doubling rate: Defined as how dB value and exposure duration are exchanged or traded. (Dosimeters use 3 or 5 dB rate). OSHA recommends using a 5 dB rate.

Frequency: the measure of the rapidity of alterations of a periodic acoustic signal, expressed in cycles per second, or Hz. Commonly known as pitch.

Hearing loss prevention program (HCP): A hearing loss prevention program is required by the Hearing Conservation Amendment (1983) which requires that a hearing conservation program be administered when employee noise exposures are 85 dBA TWA on slow meter response. This corresponds to a 50% noise dose. This is called the OSHA action level.

Hertz (Hz): The unit of measurement of frequency, numerically equal to cycles per second.

Impact-type noise: The type of noise impact noise generated by the impact of drop hammers and punch presses on another surface. This type of noise is described as "transient" as it is less than one second in duration, which may be repeated after a delay of more than one second.

Intermittent noise: A type of noise exposure that an employee is exposed to if he/she makes trips from one type of noise to other several types during a normal working day (i.e. the inspector or facility supervisor who periodically makes trips from a relatively quiet office into noisy production areas may be subject to this type of noise).

Noise dose: The ratio, expressed as a percentage, of (1) the time integral, over a stated time or event, of the 0.6 power of the measured SLOW exponential time-averaged, squared A-weighted sound pressure and (2) the product of the criterion duration (8 hours) and the 0.6 power of the squared sound pressure corresponding to the criterion sound level (90 dB).

Noise dosimeter: An instrument that integrates a function of sound pressure over a period of time in such a manner that it directly indicates a noise dose.

Noise reduction rating (NRR): This is the HPD manufacturer's single number attenuation rating based on idealistic laboratory measurements across a range of frequencies.

Noise-induced permanent threshold shift (NIPTS): Hearing loss suffered as the result of noise exposure, all or part of which is permanent.

Octave-band analyzer: A sophisticated instrument used to determine where the noise energy lies in the pitch/frequency spectrum. Most commonly used when engineering control of noise problems is planned because industrial noise is made up of various sound volumes/intensities at various pitches/frequencies.

Peak sound level: OSHA requires that accurate sound level measurements be made of true peak SPL (i.e. OSHA requires that peak noise exposures be kept below 140 dB for impulse sound). True peak SLM readings must adequately measure a pulse of 100 microseconds in duration.

Permissible exposure limit (PEL): This is the eight-hour, time-weighted average noise level that must not be exceeded. The OSHA PEL is 90 dBA per 8-hour day with a 5 dB exchange rate.

Projected dose: Projects an 8-hour dose from the sample obtained in less than 8 hours. Most accurate if noise levels are constant.

Representative exposure: Measurements of an employee's noise dose or 8-hour time-weighted average sound level that the employers deem to be representative of the exposures of other employees in the workplace.

Sound level: A level of sound in dBA, dBB, or dBC of sound waves in the air which are referenced above the standard sound pressure level of 20 µPa.

Sound level meter (SLM): This is the basic instrument used to measure sound pressure variations in the air.

Sound pressure level (SPL): Measured in decibels, it is 20 times the logarithm to the base 10 of the ratio of the pressure of a sound to the reference pressure of 20 m Pa.

Temporary threshold shift (TTS): Hearing loss suffered as the result of noise exposure, all or part of which is recovered a period of time after removal from the noise source.

Time-weighted average (TWA): The sound level which, if constant over an eight-hour exposure, would result in the same noise dose as is measured.

Training program: A training program is required annually, concerning effects of noise on hearing, use of hearing protective devices, and the purpose/necessity of audiometric testing.

1. Myth: “Use of hearing protection makes communication difficult.” 

TRUTH: For individuals with normal hearing, the use of HPDs may help provide improved communications when sound levels are greater than approximately 85 dBA. (Berger, 2010). This is due to the fact that, when exposed to high levels of noise, the ear becomes overloaded and sound is distorted, reducing the ability to accurately discriminate different sounds. The use of HPDs helps reduce sound levels, allowing the ear to operate more efficiently. This effect is similar to the use of sunglasses to help improve vision in very bright light, high glare conditions. It’s helpful to caution new HPD users that it may take a few days or weeks to adjust to hearing through HPDs. 

However, for individuals with moderate-to-severely-impaired hearing, the use of HPDs may decrease the ability to communicate effectively. In these cases, some improvement in communication may be possible when hearing protectors with uniform attenuation are worn. Flat or uniform-attenuating hearing protectors use mechanical means to filter the sound and provide nearly equal attenuation across the audible frequency range (OSHA 2005). HPDs with electronic speech enhancement capabilities may help as well. 

In any case, the idea of going without HPDs in order to communicate better should be rejected. In addition to the overloading of the ears, described above, unprotected noise exposure is likely to result in NIHL which can cause even greater difficulty communicating regardless of the noise level.

2. Myth: “I have already lost some of my hearing; hearing protection won’t help me anymore.” 

TRUTH: The use of HPDs provides several benefits with respect to existing hearing loss. First, proper use of HPDs will help prevent individuals from developing temporary NIHL and may allow existing temporary hearing loss to recover before becoming permanent. Second, although use of HPDs cannot restore normal hearing, they may help prevent additional hearing loss. People with existing hearing loss are susceptible to additional NIHL. The progressive nature of NIHL is illustrated in Figure 1. Initially, hearing damage occurs at higher frequencies. As the unprotected exposure continues, the damage and hearing loss spread to the lower frequencies. Eventually, most of the frequencies that are essential to understanding speech (500 Hz to approximately 3000 Hz) may be affected.

3. Myth: “Earmuffs block out more noise than earplugs.”

TRUTH: Bigger is not necessarily better when it comes to hearing protection. Actually, the amount of sound blocked by HPDs depends not only on the NRR of the device but also on how well they fit the wearer, and how motivated he or she is to wear them correctly.  Keep in mind that other factors aside from attenuation need to be considered when selecting a HPD. For example, comfort and the suitability of the HPDs for the intended application can affect how well HPDs are worn in a particular application.

4. Myth: “I will hurt my ears if I blow my nose while wearing earplugs.” 

TRUTH: No. Wearing earplugs is not likely to have an effect on pressure changes in the middle ear related to blowing your nose. (Berger, 1982). This is because the earplug is inserted into the external ear canal which is separated from the middle ear by the eardrum. However, even when a person has a perforated eardrum(s), earplug use is not likely to cause an increase in pain during nose blowing.

from ISHN 6/1/11 by Scott Shinn, CIH

References 

Berger, E. H. (2010). Hearing Through the Protectors. Industrial Hygiene News. July/August 2010, Vol. 33 No. 4, 8 -14.
Berger, E. H. (1993). E-A-RLOG 20—The Naked Truth About NRRs. Retrieved from www.e-a-r.com/hearingconservation Taylor, W., Pearson, J., Mair, A., and Burns, W. (1965). Study of Noise and Hearing in Jute Weaving. J. Acoust. Soc. Am., Vol. 38, 113-120.
U.S. Department of Labor. Occupational Safety and Health Administration. Hearing Conservation for the Hearing Impaired Worker. Washington, D.C. Safety and Health Information Bulletin 12-27-2005.

Is training mandatory? If so, when? Yes. Persons enrolled in Hearing Loss Prevention are required to both an annual audiogram (hearing test) and training.

Class length: Included with an annual audiogram.

Available online: Yes.

When is refresher training required? Annually.

Please see the online class schedule for more information.

Hearing Loss Prevention provides worksite consultations to evaluate noise levels and offers solutions to reduce occupational noise exposures.

If you have any noise concerns or questions, please call 540-231-3600.

Medical Services provided by Environmental Health & Safety are done at the Corporate Research Center, 2020 Kraft Drive, Suite 2100. Visit their website for directions to the Corporate Research Center.

For questions, contact Juliet Dadras, 540-231-8733 or mjdadras@vt.edu.

Noise from sonicators is best controlled using the manufacturer’s enclosures. If an enclosure is available its proper and intended use should be required. Barriers can be effective since high-frequency sound is very directional. Efficient procedures that minimize exposure are also useful.

ACGIH TLVs (Threshold Limit Values) provide specific best practice guidance on ultrasound exposure in contrast to OSHA’s Hearing Conservation Standard. There are ceiling TLVs of 105 dB as well as 8-Hour TWA values for 10, 12.5, 16,20 kHz mid-frequency third-octave bands. Our sound level meter can measure these frequencies.

The TLV recognizes that:

“Subjective annoyance and discomfort may occur in some individuals at levels between 75 and 105 dB for the frequencies from 10 kHz to 20 kHz especially if they are tonal in nature. Hearing protection or engineering controls may be needed to prevent subjective effects.”

What does this mean? People may detect and dislike sonicator noise but it is not a known health effect until 105 dB ceiling or 88-94 dB 8-h TWA (depending on frequency). Voluntary use of hearing protection (probably muffs for a short duration and/or infrequent tasks) should be encouraged for those experiencing nuisance noise. But mandatory use of hearing protection should be reserved for those installations that met or exceed that TLV. Engineering controls based on the manufacturer’s recommendations should be the primary control method.

At work, some common sources of noise exposure may include:

• Power tools: Saws, compressed air hoses, lawnmowers, and trimmers.
• Heavy equipment: Tractors and other farm equipment.

At home, some common sources of noise exposure may include:

• Power tools: Saws, lawnmowers, and trimmers.
• Hobbies: Woodworking, racing, and hunting.

It is important to protect your ears both at work and at home. Always wear proper hearing protection.

Hearing Loss Prevention training helps you learn:

• About the effects of noise on hearing;
• How to select and use hearing protection devices properly;
• Responsibilities under the OSHA Hearing Conservation regulation; and
• Results of workplace noise measurements.

The Hearing Loss Prevention (HLP) was created by Environmental Health and Safety to prevent Virginia Tech employees from developing noise-induced hearing loss as a result of excessive on-the-job noise exposure. The Virginia Tech HLP promotes compliance with the requirements of the Department of Labor Occupational Noise Exposure Standard (29 CFR 1910.95) promulgated by OSHA.

Environmental Health and Safety measures noise levels at no cost to the faculty and staff of Virginia Tech.

Hearing Loss Prevention training is provided during the scheduled annual audiogram or the training can be taken online at any time.