February 14, 2005

Ms. Kathleen Brunell, RN
All Saints Medical Group
2405 Northwestern Ave.
Racine, WI 53404

Dear Ms. Brunell:

Thank you for your July 8, 2004 letter to the Occupational Safety and Health Administration (OSHA) regarding audiometric testing rooms and compliance with the Occupational Noise standard, 29 CFR 1910.95. In your letter, you have specifically asked how often the audiometric testing room must be evaluated per the specifications in Appendix D of the Occupational Noise standard. This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any question not delineated within your original correspondence.

The intent of the ambient noise level requirements in the OSHA standard is to assure that the hearing test is conducted in an environment that will assure valid and accurate test results. Paragraph 1910.95(h)(4) requires that audiometric examinations be administered in a room meeting the requirements listed in Appendix D. This implies that the test environment must be in compliance with the stated background levels every time an audiometric test is performed.

There are different types of testing environments utilized in hearing conservation programs (i.e., sound-proof booth, mobile van, and an open room. However, every audiometric test must be performed in rooms meeting the requirements listed in Appendix D so that measured thresholds between tests reflect real hearing change rather than measurement error.

For a sound booth that never moves once it is stationed, the ambient noise levels may not need to be measured more than once a year, typically at the time of the annual and/or exhaustive calibration. However, an evaluation should also be done if there are changes in the outside environment that could have changed the internal ambient background levels. Equipment is available that performs ambient noise level monitoring continuously during hearing testing. Also, newer computerized audiometers frequently incorporate the ambient noise level monitoring into the hearing test itself and will only accept responses to test signals when the ambient noise is within acceptable limits.

To meet the requirements of Appendix D for a mobile van, as a minimum, it may be necessary to do ambient testing whenever the van is relocated to a new location at a minimum. To ensure that the hearing test results are valid each time, it is advisable to check ambient noise levels every day you do audiometric testing along with the daily calibration check using a bioacoustical simulator. As stated above, you may also use the newer computerized audiometers that incorporate ambient noise level monitoring into the hearing test itself. If you notice changes in the external environment, such as greater truck traffic, you might also consider moving the van to a quieter location.

Conducting audiograms in an open room environment can also be difficult. Noise levels can change constantly depending on what is going on in the immediate surrounding area (i.e., outside traffic, air conditioning going on and off, disturbing noise from the clanking of shoes, phones ringing, etc.). In this situation, background levels may need to be monitored whenever an audiometric test is administered.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. 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 http://www.osha.gov. If you have any further questions, please feel free to contact the Office of Health Enforcement at (202)693-2190.

Sincerely,

Richard E. Fairfax, Director
Directorate of Enforcement Programs