The Occupational Safety and Health Administration’s (OSHA) hearing conservation program is designed to protect workers that are exposed to occupational noise from suffering material hearing impairment. OSHA requires that employers establish and maintain audiometric testing program, which includes baseline audiograms, annual audiograms, training, and follow-up procedures, for workers exposed to significant occupational noise, even if they are subject to such noise exposures over their entire working lifetimes. Audiometric testing not only monitors the sharpness and acuity of an employee’s hearing over time, but also provides an opportunity for employers to educate employees about their hearing and the need to protect it.
The two types of audiograms required in the hearing conservation program are baseline and annual. The baseline audiogram is the reference audiogram against which future (annual) audiograms are compared. The essential elements of an audiometric testing program include:
Making audiometric testing available at no cost to all employees who are exposed to an action level of 85 dB or above, measured as an 8-hour time weighted average (TWA).
Having a licensed or certified audiologist (i.e., a specialist dealing with an individual having impaired hearing), an otolaryngologist (i.e., a physician specializing in the diagnosis and treatment of disorders of the ear, nose, and throat), or a physician responsible for the program.
Both professionals and trained technicians may conduct audiometric testing. The professional in charge of the program does not have to be present when a qualified technician conducts tests. The professional’s responsibilities include overseeing the program and the work of the technicians, reviewing problem audiograms, and determining whether referral is necessary.
Baseline audiograms must be provided within six months of an employee’s first exposure at or above an 8-hour TWA of 85 dB. An exception is the use of mobile test vans to obtain audiograms. In these instances, baseline audiograms must be completed within one year after an employee’s first exposure to workplace noise at or above a TWA of 85 dB.
Employees must be fitted with, issued, and required to wear hearing protectors for any period exceeding 6 months after their first exposure until the baseline audiogram is conducted.
Employees must not be exposed to workplace noise for 14 hours preceding the baseline test; however, appropriate hearing protectors can serve as a substitute for this requirement and can be worn during this time period.
Annual audiograms must be conducted within one year of the baseline to identify deterioration in hearing ability so that protective follow-up measures can be initiated before hearing loss progresses. Annual audiograms must be routinely compared to baseline audiograms to determine whether the audiogram is valid and to determine whether the employee has lost hearing ability, i.e., if a standard threshold shift (STS) has occurred. STS is an average shift in either ear of 10 dB or more at 2,000, 3,000, and 4,000 hertz. An averaging method of determining STS was chosen because it diminished the number of persons falsely identified as having STS and who are later shown not to have had a change in hearing ability. Additionally, the method is sensitive enough to identify meaningful shifts in hearing early on.
The employee must be given a referral for further testing when test results are questionable or when problems of a medical nature are suspected.
If additional testing is necessary or if the employer suspects a medical pathology of the ear is caused or aggravated by the wearing of hearing protectors, the employee should be referred for a clinical audiological evaluation or otological exam, as appropriate.
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