Hearing Conservation

1. Hearing Conservation

2. Introduction Noise pollution is everywhere. Exposure to high levels of noise can cause hearing loss, ringing in the ear and physical and psychological stress. Additionally, excessive noise can reduce productivity, interfere with communication, and contribute to accidents and injuries at the workplace. Hearing loss or hearing damage is one of the most common health problems in America. It is estimated that 30 million workers in the U.S. are exposed to hazardous noise. To provide the proper protection, employees must have a good knowledge and understanding of noise exposure and protective measures. This training program was created to help ensure you understand the requirements for hearing protection and working safely in noisy work settings.

3. Scope and Application OSHA requires employers to determine if employees are exposed to excessive noise levels. When employees are subjected to excessive noise levels, feasible administrative or engineering controls must be used. The incidence of noise-induced hearing loss can be reduced or eliminated through the successful application of engineering controls and hearing conservation programs. Where controls are not sufficient, employers must implement an effective hearing conservation program.

4. Definitions • Sound: The physical phenomenon that stimulates our sense of hearing. It is an acoustic wave that results when a vibrating source, such as machinery, disturbs an elastic medium, such as air. • Frequency: Is measured in units known as a Hertz and is the number of waves or vibrations that occur per second. Hertz is abbreviated Hz. • Decibel: The unit used to measure sound levels, abbreviated dB. Sound measurements are taken while standing near the sound.

5. Definitions • A-Weighted Decibel: The unit used to measure sound levels adjusted to mimic how the ear perceives the sound, abbreviated dBA. • Action Level: An 8-hour time-weighted average of 85 decibels measured on the A-scale, slow response, or equivalently, a dose of fifty percent. • Time-weighted average sound level: The sound level, which if constant over an 8-hour exposure, would result in the same noise dose as is measured, abbreviated TWA.

6. The Ear Your ear allows you to hear sound and noise. Sound is created when acoustic waves are felt by the eardrum. The number of waves or vibrations that occur per second are known as the frequency of the sound. The frequency is measured in Hertz (Hz). One Hertz equals one vibration or wave. The human ear can perceive frequencies between approximately 20 and 20,000 Hz but the range varies greatly between different people. The ability to perceive higher frequencies decreases as people age. The ear is made up of three different parts.

7. The Ear • External Outer Ear – Receives acoustic wave and directs it to the eardrum. • Air-Filled Middle Ear – Converts and amplifies the modified acoustic wave to a vibration of the eardrum and transmits to the inner ear. • Fluid-Filled Inner Ear – Transforms the mechanical movement of the wave into nerve impulses that travel to the brain, which perceives and interprets the impulse as sound.

8. Hearing Loss When you are exposed to extremely loud sounds or loud sounds that last a long time, some damage can occur resulting in permanent or temporary hearing loss. This is known as Noise Induced Hearing Loss or NIHL. Noise-induced hearing loss is one of the more common occupational illnesses. It usually is ignored because there is no visible effects, tends to develop over a long period of time and except in rare cases, there is no pain.

9. Hearing Loss • The loudness of sound is measured in decibels (dB). For example, normal conversation is 60 dB and city traffic noise can be 85 dB. Noises that can cause Noise Induced Hearing Loss include motorcycles, woodworking tools, machinery, firecrackers and fire arms. • Exposure to noise levels over a long period of time at or above 85 dB can cause hearing loss. The louder the sound, the shorter the exposure time it takes to cause hearing loss. Most people do not feel pain in the ears until noise levels reach approximately 120 dB. The range between 85 and 120 dB is a danger zone where damage can occur and not be realized. • Sounds may become distorted or muffled if NIHL exist. The person may also find it difficult to understand speech. Hearing loss is often accompanied by ringing, buzzing or roaring sounds in the ear. This is known as tinnitus and is the most common symptom of NIHL.

10. Hearing Loss • Tinnitus usually indicates the noise level is too loud. • Noise Induced Hearing Loss does not discriminate against age. There are many known cases from children to the elderly. Exposure can happen in a variety of places such as the work environment, recreational activities or at home. • NIHL is 100% preventable with training and the use of hearing protection. Once NIHL is acquired though, it is permanent and irreversible.

11. Types of Hearing Loss • Hearing loss is usually classified as either conductive or sensorineural. A combination of both types is possible. • Conductive hearing loss is a result of any condition in the outer or middle ear that interferes with sound passing to the inner ear. This type of hearing loss generally involves a reduction in sound level, or the ability to hear ‘soft’ sounds. Excessive wax build-up in the auditory canal or fluid in the middle ear is a couple of examples of conductive hearing loss. Work-related conductive hearing loss is not common, although it may occur occasionally as the result of accidents involving: • An eardrum rupture caused by a blow to the head. • b) Explosions. • c) Penetration of the eardrum by a sharp object or fragment. • Many conductive hearing losses are reversible through medical or surgical treatment.

12. Types of Hearing Loss • Chronic noise-induced hearing loss is a permanent sensorineural condition that cannot be treated medically. Such loss can be mild, moderate or severe, including total hearing loss. "Sensory" hearing loss is associated with irreversible damage to the inner ear or the nerve pathways from the inner ear to the brain. It is initially characterized by a declining sensitivity to high-frequency sounds, usually at frequencies above 2,000 Hertz (Hz). • A combination of both conductive and sensorineural hearing loss can occur. This type of hearing loss is usually referred to as mixed hearing loss.

13. Effects of Excessive Noise Exposure Even though noise-induced hearing loss has no visible effects or any pain, there are some very real consequences. The act of communicating is often negatively affected and diminishes over time.A progressive loss of socialization and responsiveness to the environment also occurs quite often with NIHL. When hearing loss is above 2,000 Hertz it affects the ability to understand or discriminate speech. As the loss moves into lower frequencies, it begins to affect the ability to hear sounds in general. The effects of noise can be simplified into three general categories: Primary Effects, Effects on Communication and Other Effects.

14. Effects of Excessive Noise Exposure • Primary Effects • The primary effects of excessive noise exposure may include: • a) Acoustic trauma which refers to a temporary or permanent hearing loss due to a sudden, intense acoustic or noise event, such as an explosion. • b) Tinnitus which describes the condition of "ringing in the ears." Many people experience tinnitus during their lives. • Individuals often describe the sound as a ring, buzz, hum, roar or whistle.

15. Effects of Excessive Noise Exposure • The predominant cause of tinnitus is long-term exposure to high sound levels, though it can also be caused by short-term exposure to very high sound levels, such as gunshots. Non-acoustic events, such as a blow to the head, dietary issues, stress, jaw joint disorders, debris on the eardrum, or prolonged use of aspirin may also cause tinnitus. • Many people experience tinnitus during their lives. Most of the time the sensation is only temporary, however, it can be permanent and debilitating.

16. Effects of Excessive Noise Exposure • c) A Noise-Induced Temporary Threshold Shift (NITTS) is a temporary loss in hearing sensitivity. With NITTS, hearing sensitivity will return to the pre-exposed level in a matter of hours or days, assuming that there is not continued exposure to excessive noise. • d) A Noise-Induced Permanent Threshold Shift (NIPTS) is a permanent loss in hearing sensitivity due to the destruction of sensory cells in the inner ear. This damage can be caused by: • Long-term exposure to noise. • Acoustic trauma.

17. Effects of Excessive Noise Exposure • Effects on Communication and Performance • Excessive noise exposure can have a negative effect on a employee’s ability to communicate as well as their job performance. • a) Can cause individuals to feel isolated from coworkers. • b) Employees can be easily annoyed. • c) Employees may have difficulty concentrating. • d) Can cause higher absenteeism and accidents. • Other effects may include stress, muscle tension, ulcers, increased blood pressure, and hypertension. Often-times employees will not know the reason behind their changed behaviors.

18. Evaluating Noise Exposure Levels • The first step towards solving a noise problem is to define it. Determining exposure levels is necessary to implement a successful hearing training program. • There are various factors that may indicate noise is a problem in the workplace. • Noise conditions that make normal conversation difficult. • Adverse reactions or behaviors in the workplace. • Reduced job performance or production.

19. Evaluating Noise Exposure Levels • A walkaround survey should be performed. Sound level meter measurements and duration of exposure estimates are sufficient to determine if additional monitoring is needed. If the results indicate a time-weighted average (TWA) exposure of 80 dBA or more, then additional noise monitoring should be performed. • Establish a sampling protocol to measure sound levels. • Inform and educate all employees about the noise monitoring protocol. • Sample noise exposure of representative employees from all areas that are potentially overexposed. • Conduct sampling for an appropriate length of time to establish whether exposures are above permissible limits. • TWA exposures at or above 85 dBA, also referred to as the action level, require a hearing conservation program. • TWA exposures exceeding the Permissible Exposure Level (PEL) require feasible engineering or administrative controls be implemented.

20. Evaluating Noise Exposure Levels • A. Instruments Used to Measure Sound • Three different instruments are generally used to measure sound. • Sound Level Meter • A sound level meter (SLM) is the basic instrument for investigating noise levels. • Dosimeter • Like a sound level meter, a noise dosimeter can also measure sound levels. However, the dosimeter is actually worn by the employee in order to determine the personal noise dose during the workshift or sampling period. • Octave-Band Analyzer • Octave-band analyzers are sound level meters which amplify a microphone signal and feeds it into a band-pass filter.

21. Hearing Conservation Program • Whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level of 85 dBA, OSHA requires a continuing, effective hearing conservation program be administered. OSHA states specific Hearing Conservation Program requirements for general industry, but not for the construction industry. Even so such programs should contain at least the following regardless of which industry. • A. Noise Monitoring • In order for the employer to know who must wear hearing protection and to be able to evaluate the adequacy of the hearing protection used, the noise created by different machines and operations should be known. • It is the responsibility of the employer to implement a noise monitoring program as part of the hearing conservation program. The program is only necessary if test results show that employees are exposed to an 8 hour time-weighted average of 85 dB.

22. Hearing Conservation Program • Monitoring must be repeated whenever there is a change in production, process, equipment or controls that increases the noise to the extent that: • Additional employees may be exposed, or • Hearing protection is rendered inadequate. • Employees must have the opportunity to observe any tests conducted.

23. Hearing Conservation Program B. Audiometric Testing Audiometric testing monitors an employee's hearing over time and will detect any changes. A baseline test must first be performed to compare subsequent test. The presence of a threshold shift can be determined by such testing. This also provides an opportunity for employers to educate employees about their hearing and the need to protect it.

24. Hearing Conservation Program • Employers must establish and maintain an audiometric testing program for all employees exposed at or above the action level • of 85 dBA. • Audiometric tests must be performed by a licensed professional. • Employees should provide the examiner with any history of disease, treatment and current conditions. • Exams must be performed annually to determine if the employee is experiencing any hearing loss due to exposure to noise. If a threshold shift is present, the employer must provide additional means of hearing protection.

25. Hearing Conservation Program • C. Hearing Protection • Hearing protection devices (HPDs) are considered the last option to control exposures to noise. HPDs are generally used during the time necessary time to implement engineering or administrative controls, or when such controls are not feasible. • Employers must make HPDs available to all employees exposed at or above the action level. These must be provided at no cost to employees and must be replaced as necessary. • Employees must be given the opportunity to select their HPDs from a suitable variety. Generally, this should include a minimum of two devices, representative of at least two different types. • Employers must provide training in the use and care of all HPDs provided to employees. • Employers must ensure proper initial fitting of HPDs and supervise their correct use.

26. Hearing Conservation Program • D. Training • Employers should institute an annual training program for all employees with noise exposures at or above the action level. • Training should be conducted annually. • Employees must be trained to understand the effects of noise on hearing, purpose and use of protectors, different characteristics of various HPDs and know how to select, fit, use and care for them. • Records must be kept of employees who have received the training. These records must include: • Name of employees trained. • Job classifications of each employee. • Date of training. • Personnel performing training.

27. Hearing Conservation Program • E. Record Keeping • The employer must maintain appropriate and accurate records of all noise measurements, audiograms and training. • The forms for audiograms must include: • Name and job classification of employee. • Date of audiogram. • The examiner's name. • Date of the last acoustic or exhaustive calibration of the audiometer. • Employee's most recent exposure assessment.

28. Hearing Conservation Program • Records are required to be kept for a period of time. • Noise exposure measurement records must be kept for two years. • Audiometric test records must be retained for the duration of an affected employee's employment. • All materials that are kept pertaining to hearing conservation must be readily available for employees, former employees, representatives and the Assistant Secretary upon request. • These records must be transferred to the successor employer if the current employer ceases to do business. The successor employer will then be responsible for maintaining the records for the remainder of the period required.

29. Hearing Protection • There are many types of hearing protection. The four basic types of ear protection include foam plugs, pre-molded plugs, canal caps and earmuffs. The best hearing protector is the one that is comfortable, convenient and one you will wear every time you are in an environment with hazardous noise. • Foam ear plugs are designed to expand and fit the contours of the ear canal To insert them into the ear, simply roll them between your thumb and fingers or in the palm ofyour hands. The final result should be a smooth tube thin enough sothat about half the length will fit • easily into your ear canal. The foam will then expand to fit the canal.

30. Hearing Protection Pre-molded plugs are usually made from silicone, plastic or rubber and usually come in many different sizes. The major problem with these is that both ear canals may not have the same shape. A person may need a different size plug for each ear. The plugs should seal the ear canal without being uncomfortable. To insert this type of plug you must reach over your head with one hand and pull back on the ear to open the canal more. Then with the other hand, place the plug in the canal, gently rocking it back and forth until the canal is sealed.

31. Hearing Protection • C. Canal caps often resemble ear plugs on a flexible plastic or metal band. The main advantage canal caps offer is convenience. When it's quiet, employees can leave the band hanging around their necks. They can quickly insert the plug tips when hazardous noise starts again. Some people find the pressure from the bands uncomfortable. Not all canal caps have tips that adequately block all types of noise. Generally, the canal caps tips that resemble stand-alone earplugs seem to block the most noise.

32. Hearing Protection • D. Earmuffs are manufactured in many different models to fit most people. They block noise by completely covering the outer ear. Some muffs have electronic components that cancel sound and/or allow the wearer to communicate to others. Ear muffs lose their effectiveness when the wearer has a thick beard or sideburns. The hair prevents the muffs from sealing against the area surrounding the ear. In some environments, the earmuffs can feel hot and heavy.

33. Conclusion The ear is a sensitive part of the body that is very susceptible to damage caused by exposure to loud sounds for a continuous period of time or very loud sounds. Hearing loss is 100% preventable when employees are properly trained and use the proper hearing protection. There are many types of hearing protection available today. The most effective one is the one that fits properly.