Audiometric testing is a series of hearing tests that measure a person’s ability to hear sounds at a range of frequencies and volumes. For workers, it is used to detect changes in hearing over time which could indicate that the worker’s hearing has been damaged. This can be caused by exposure to high noise levels or certain chemicals. According to the National Institute of Occupational Safey & Health (NIOSH) about 25% of workers have been exposed to hazardous noise about 20%of noise-exposed tested workers have a significant hearing impairment.
OSHA requires that annual hearing testing is conducted on employees whose exposure to noise exceeds the Action Level of 85 decibels for an 8-hour shift on the A scale (dBA) or a 50 percent dose as required under 1910.95 for general industry and 1926.52 for construction. Within 6 months of an employee’s first exposure at or above the action level, the employer must establish a valid baseline audiogram. This is part of a mandatory hearing conservation program.
Audiometric testing must be conducted by a trained technician, audiologist, otolaryngologist, or other physician with a calibrated audiometer in a testing booth or room with measurements of background sound pressure levels conducted before testing.The hearing tests is reviewed by an audiologist, otolaryngologist, or other physician and compared to an employee’s baseline audiogram to determine if the audiogram is valid and if a standard threshold shift (STS) has occurred. An STS is a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either ear. The hearing test is repeated within 30 days and if the STS persists the employee may be required to wear hearing protection. The STS should be recorded on the facility log of illnesses and injuries unless the physician or audiologist determines that hearing loss is cause by non-work activities in which case the STS may be disregarded.
In order to control exposure to noise, employees must be provided with hearing protection such as plugs and/or muffs and necessary training if the Action Level is exceeded or mandatory usage if the Permissible Exposure Limit of 90 dBA or a 100 percent dose is exceeded. Although hearing protection can be effective against high noise, 53 percent of noise-exposed workers report not wearing hearing protection. A better strategy is to reduce exposure by installing engineering controls such as enclosures and barriers or administrative controls such as moving the employee away from the noise source or reducing the period of exposure.
Audiometric testing is a necessary part of a hearing conservation program. It can help employees and employers identify hearing loss early on which can allow for changes that reduce exposure to noise. It can help employees understand the effects of noise and how they can best protect themselves from damage to their hearing.
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