• Work-related hearing loss above the indicated threshold must be recorded on the OSHA 300 Log.

Noise-induced hearing loss is a serious and irreversible condition. However, it is not the type of occupational injury that typically requires days away from work for recuperation. All work-related hearing losses of 10 decibel shifts that result in a total 25 decibel shift above audiometric zero have to be recorded on the Occupational Safety and Health Administration (OSHA) 300 Log.

Audiometric zero and STS

A standard threshold shift (STS) is a change in hearing threshold, relative to an employee’s baseline audiogram (hearing test), averaging 10 decibels or more at 2,000, 3,000, and 4,000 hertz in one or both ears. If an employee’s audiogram reveals that a work-related STS has occurred in one or both ears, and the total hearing level is 25 decibels or more above audiometric zero in the same ear(s) as the STS, the case is recordable.

If an employee has a recordable STS, employers must document the case by checking the “hearing loss” column on the OSHA 300 Log.

Retesting

Retesting allows employers to exclude false positive results and temporary threshold shifts from the data. If the employee’s hearing is retested within 30 days of the first test, and the retest does not confirm the STS, the employer is not required to record the hearing loss case on the OSHA 300 Log. However, if the retest confirms the STS, the employer must record the hearing loss illness within seven calendar days of the retest.

Hearing loss that occurs with aging

Employers may take into account the hearing loss that occurs as a result of the aging process and retest an employee who has an STS on an audiogram to ensure that the STS is permanent before recording it. When comparing audiogram results, results may be adjusted for the employee’s age when the audiogram was taken using Tables F-1 or F-2, as appropriate, in Appendix F of the Occupational Noise Exposure standard.

Noise dose

Hearing loss is presumed to be work related if the employee is exposed to noise in the workplace at an eight-hour time-weighted average of 85 decibels or greater, or to a total noise dose of 50 percent, as defined in OSHA’s noise exposure standard.

Noise dose is defined as the amount of actual exposure to noise relative to its permissible exposure limit. A dose greater than 100 percent represents exposure above the limit. For hearing loss cases where the employee is not exposed to this level of noise, employers should refer to the rules in 1904.5 to determine if the hearing loss is work-related.

If a physician determines that the hearing loss is not work related or has not been significantly aggravated by occupational noise exposure, the employer is not required to consider the case work related or to record it on the OSHA 300 Log. Some examples are if the hearing loss occurs before the employee is hired, or the hearing loss is unrelated to workplace noise, such as off the job traumatic injury to the ear or infections.