When an employee experiences a Standard Threshold Shift
OSHA’s occupational noise exposure standard, 1910.95, requires employers to establish and maintain a hearing conservation program for all employees whose noise exposures equal or exceed an 8-hour time-weighted (TWA) average of 85 decibels (dB). Those affected employees must have a baseline audiogram conducted within 6 months of first exposure greater than 85 dB, as well as annually thereafter. The employer is required to take further action should an employee experience a change in hearing threshold relative to their baseline audiogram, also known as a Standard Threshold Shift (STS).
A Standard Threshold Shift is a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000, and 4000 Hertz (Hz) in either ear. While employers may consider natural hearing loss caused by aging when determining whether an STS has occurred, occupational exposure to loud noises, ototoxic chemicals, and/or ill-fitting PPE (or lack of PPE) are the main reasons.
If an employee has experienced a work-related STS, the employer should be aware of the following:
- The employer may obtain a retest within 30 days and consider the results of the retest as the annual audiogram.
- The employee must be informed of the STS in writing, within 21 days of the determination.
- The employer must ensure employees not using hearing protection get fitted with hearing protection, trained in their use and care, and required to use them.
- The employer must ensure employees already using hearing protection get refitted and retrained in their use. If necessary, employers must provide hearing protection with greater attenuation.
- The employer must ensure that hearing loss is recorded on the OSHA 300 log as a recordable injury if the STS reveals that the employee’s total hearing level is 25 dB or more above audiometric zero (averaged at 2000, 3000, and 4000 Hz) in the same ear as the STS.
- The employer may not use the age adjustment when determining whether the employee’s total hearing level is 25 dB or more above audiometric zero.
- The employer may choose to retest the employee’s hearing within 30 days of the first test. If the retest does not confirm the recordable STS, the employer is not required to record the hearing loss case on the log. If the retest does confirm the recordable STS, the employer must record the hearing loss illness within seven calendar days of the retest.
A successful hearing conservation program repeatedly and proactively monitors noise exposure whenever there is a change in production, process, equipment, or controls. By designing a sound sampling strategy, an employer can stay ahead of any potential work-related hearing loss.