Occupational Noise Exposure
As used in this section, a
STANDARD THRESHOLD SHIFT (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.
In determining whether a
STS has occurred, allowance may be made for the contribution of aginq (presbycusis)
to the change in hearing level by correcting the annual audiogram...
If the annual audiogram
shows that an employee has suffered a STS, the employer may obtain a retest
within 30 days and consider the results of the retest as the annual
If a comparison of the
annual audiogram to the baseline audiogram indicates a STS ... has occurred, the
employee shall be informed of this fact in writing, within 21 days of the
Unless a physician
determines that the STS is not work related or aggravated by occupational noise
exposure, the employer shall ensure that the following steps are taken when a
Employees not using hearing protectors shall be fitted with hearing
protectors, trained in their use and care, and required to use them.
Employees already using hearing protectors shall be refitted and
retrained in the use of hearing protectors offering greater attenuation if
The employee shall be referred for a clinical audiological evaluation or
an otological examination, as appropriate, if additional testing is necessary or
if the employer suspects that a medical pathology of the ear is caused or
aggravated by the wearing of hearing protectors.
The employee is informed of the need for an otological examination if a
medical pathology of the ear that is unrelated to the use of hearing protectors
If subsequent audiometric
testing of an employee whose exposure to noise is less than an 8-hour TWA of 90
dB indicates that a STS is not persistent, the employer:
Shall inform the employee of the new audiometric interpretations; and
May discontinue the required use of hearing protectors for that
An annual audiogram may be substituted
for the baseline audiogram when, in the judgment of the audiologist,
otolaryngologist or physician who is evaluating the audiogram:
The STS revealed by the audiogram is persistent; or
The hearing threshold shown in the annual audiogram indicates
significant improvement over the baseline audiogram.
does not mean the original baseline can be discarded. It does mean an annual can
be substituted, to avoid constant referrals due to a persistent STS).