Q. What is a hearing shift and does this apply to workers?
A. The hearing shift, or standard threshold shift, is in reference to an employee’s loss of hearing. Once it’s determined that an employee or employees are exposed to noise levels above OSHA’s action level of 85 dBA the employer needs to take certain actions. OSHA’s action level is the level of noise exposure where the employer must enlist a hearing conservation program. One of the elements of the hearing conservation program is audiometric testing. This is where the employees get their hearing tested 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. The first or original audiometric test is considered the baseline audiogram. The baseline needs to be determined within 6 months of an employee’s first exposure at or above the action level. The baseline audiogram will be then compared against all subsequent audiograms.
After the baseline audiogram has been determined, new audiograms for each employee exposed at or above the action level must be obtained at least annually. These audiograms will then be compared to the baseline to see if there has been any changes in the employees hearing. The standard threshold shift comes into play when there’s a change in the hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either ear. If it has been determined that an employee experienced a standard threshold shift controls need to be implemented to reduce the employees exposure to 85 dBA or lower.
