May 24, 1983

Mr. David Efros
President
CSDS Occupational Health Services
P.O. Box 26112
Tempe, Arizona 85282

Dear Mr. Efros:

Thank you for your letter of May 5, 1983, asking for a clarification of the hearing conservation amendment provisions for baseline, annual, and revised baseline audiograms.

An annual audiogram must be taken and compared against the baseline audiogram to determine whether a standard threshold shift (STS) has occurred. There is no requirement for 14 hours without exposure to workplace noise for annual audiograms as there is for baseline audiograms. A temporary threshold shift (TTS) could possible contaminate the annual audiogram if an employee was exposed to workplace noise prior to taking the audiogram. It is this audiogram which is compared to the baseline audiogram to determine whether an STS has occurred. The audiologist, otolaryngologist, or physician cannot override this STS determination simply because of possible TTS contamination. Only a retest audiogram, taken within 30 days of the annual audiogram, can be used to replace the annual audiogram and the STS determination.

If TTS contamination is a problem, the retest audiogram should be preceeded by 14 hours free from workplace noise, but this is not required by the standard. If no retest is done, the annual audiogram and its STS determination are conclusive, and the follow-up procedures and written notification of the STS determination to the employee must be done. The annual audiogram can be substituted for the baseline audiogram when the audiologist, otolaryngologist, or physician who evaluates the audiogram determines that the STS is persistent.

I hope this information has clarified the baseline, annual, and retest audiogram requirements of the hearing conservation amendment for you. If you have any further questions, please do not hesitate to contact us.

Sincerely,



R. Leonard Vance, Ph.D.
Director
Health Standards Programs