Standard Interpretations - Table of Contents
• Standard Number: 1910.95

March 18, 1987

Ms. Mari Franqui, M.A.
Advantage Health Systems, Inc.
Suite 350
14062 Denver West Parkway
Golden, Colorado 80401

Dear Ms. Franqui:

This is in response to your letter of December 17,1986, regarding the calculating of hearing threshold shift.

In a telephone conversation with a member of my staff you indicated that on occasion you test individuals who cannot hear the maximum 4,000 Hertz signal that your audiometers produce, which is 99 dBA, yet these individuals can hear the 2,000 and 3,000 Hertz signals. You inquire in your letter about the appropriate method for calculating the hearing threshold shifts they incur.

The Occupational Safety and Health Administration (OSHA) agrees with your opinion that the correct method of calculating the shifts is to take the average of just the measurable changes in bearing threshold occurring at 2,000 and 3,000 Hertz. The numerical value obtained by the calculation indicates a greater hearing loss than the same numerical value obtained for a normally calculated hearing shift that includes the change in hearing threshold occurring at 4,000 Hertz, however. This is so because, as you may be aware, the amount of hearing loss at 4,000 Hertz is typically greater than the amount of loss at the 2,000 and 3,000 Hertz frequencies.

Therefore, the followup procedures presented at 29 CFR 1910.95(g)(8) should be triggered by a calculated change in hearing threshold of less than 10 dB the calculated change must be, because this issue was not addressed during rulemaking proceedings. Accordingly, at the present time, the amount of calculated change in hearing threshold that triggers followup procedures is left to the professional judgment of the audiologist, otolaryngologist, or physician responsible for the audiometric testing program.

Thank you for contacting OSHA on this matter.


Leo Carey, Director
Directorate of Field Operations

December 17, 1986