OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

June 4, 1986

Ms. Mari Franqui
CCC-A, Audiologist
ADVANTAGE Health Systems, Inc.
14062 Denver West Parkway, Suite 350
Golden, Colorado 80401

Dear Ms. Franqui:

This is in response to your letter of March 31 concerning persistent standard threshold shift (STS).

"Persistent STS" is a term the Occupational Safety and Health Administration (OSHA) uses to mean an STS that is subsequently confirmed by another audiogram.

If you are supervising the audiometric testing program, then, in accordance with 29 CFR 1910.95(g)(9)(i), you as an audiologist may substitute an annual audiogram for the baseline audiogram when in your judgment the annual audiogram reveals that an STS is persistent. It is not mandatory that you make the substitution, but whenever you conclude that it is appropriate, the above cited provision permits that the substitution be made.

Thank you for contacting us. If we may assist you again in the future, we shall be glad to do so.


John B. Miles, Jr., Director
Directorate of Field Operations

March 31, 1986

James Foster, Director
Office of Information & Consumer
Occupational Safety & Health
Room N-3637, U.S. Department of Labor
200 Constitution Avenue, N.W.
Washington, D.C. 20210

To Whom It May Concern:

I am an audiologist working in the field of industrial hearing conservation. I would like to receive a statement from you as to the meaning of "persistent STS" (Federal Register, Vol. 48, No. 46, page 9766).

Evidently, a "persistent STS" could be interpreted in two different ways. Could a persistent STS mean a permanent STS or a progressive hearing loss? That is, will those employees who demonstrate a progressive hearing loss (sensorineral) be considered to have a persistent STS every other year? If so, should their baseline audiograms be revised every other year?

As I interpret the standard, a persistent STS means a permanent threshold shift which has been confirmed by subsequent audiograms. An annual audiogram should not be substituted for the baseline audiogram if thresholds are fluctuating (shifting every year).

Please advise me of your interpretation of the standard. You may reach me at Advantage Health Systems, Inc.

Thank you,

Mari Franqui, M.A.
CCC-A, Audiologist