Audiometers and Audiometric Testing Rooms: Calibration and Documentation


How often does OSHA require a sound booth to be calibrated?

OSHA requires that the audiometric testing room – which can be an open room – be no louder than the maximum permissible ambient noise levels specified in the OSHA Noise Standard.  These noise levels are:

        500Hz        1000Hz        2000Hz            4000Hz         8000Hz

     40 dB SPL    40 dB SPL    47 dB SPL      57 dB SPL    62 dB SPL

 As a practical matter, it is not difficult to meet these numbers in a reasonably quiet and distraction-free room.  However, there is near universal agreement among professional hearing conservationists that these maximum permissible noise levels are too high, particularly for persons with hearing loss who often have difficulty with background noise interfering with audiometric testing.  Voluntary compliance with the more stringent criteria set forth in ANSI S3.1-1999 is recommended when feasible.  These noise levels are:

125Hz   250Hz   500Hz  1000Hz  2000Hz  4000Hz  8000Hz

39dB SPL  25dB SPL  21dB SPL 26dB SPL 34dB SPL 37dB SPL 37dB SPL

So back to the question:  how often does OSHA require measurement of background noise levels?  The answer is once, then again if something changes.

So what might change?

Relocating the booth, for one, but there is room for judgment.  If the booth is moved from one corner of the room to another, there may be no need to re-measure the background noise levels unless there is reason to believe that the noise levels are higher in the new location.

Practically, what will change the most over time is the booth itself – it will get older.  This means that the seal around the door will eventually degrade letting more sound into the booth.  More importantly, the ventilation fan will grow noisier over time and eventually need replacement.  The fans are not expensive, but can be tricky to replace.  Please have your local maintenance person give it a try as a non-ventilated sound booth can become uncomfortably warm and “stuffy” in short order.  A claustrophobic person will certainly be uncomfortable in a non-ventilated sound booth.

Bear in mind that ventilation is a major noise source when testing in an open room.  Be sure to test the background noise levels with the air conditioning/heating system on and off.  Background noise levels may be too high when the AC or heat is running.

For these reasons, it is recommended that background noise levels be measured at least every two years.  The technician providing an on-site audiometer calibration will have the necessary equipment (a rather expensive sound level meter with an octave-band analyzer) to conduct this background noise measurement.

I use a mobile service provider for annual audiometric testing.  Are they required to check background noise levels?

OSHA requires that all audiometric testing done for the purpose of compliance with the OSHA Noise Standard must be conducted in an environment where background noise levels do not exceed the maximum permissible (see the first chart above).  Mobile service providers must verify that background noise levels do not exceed the maximum, and must do this at each location where testing takes place.

Mobile services

What about documentation?

Important!  Acoustic and exhaustive audiometer calibrations must be documented on a form listing the specific functions tested and the results.  Similarly, background noise levels in the audiometric testing room must be documented as well.  This documentation is required by the OSHA Noise Standard and can be important in other legal proceedings (Workers’ Compensation, for instance).

The daily biological calibration and self-listening checks should also be documented.  This provides evidence that the audiometer functioned appropriately the day of the test.

How long should you keep these documents?  The recommended time is 30 years plus the employees time at the company- as these documents could be used in Workers’ Compensation cases involving long-term employees.

Can I do my own audiometer calibrations and testing room background noise level checks?

Certainly, you can and should do the daily listening checks described above.

There are no regulatory requirements stipulating who can and cannot do acoustic/exhaustive audiometer calibrations and background noise level checks in the audiometric testing room.  Anyone can do it with proper training and the right equipment.  The real issue is the cost of the equipment.  An audiometer calibration kit can easily run five times the cost of the audiometer.  Practically, only manufacturers and service providers doing many calibrations annually find it affordable to spend this much money on audiometer calibration equipment and to pay the cost associated with having that equipment calibrated annually.

Does Workplace INTEGRA provide these services?

Yes.  On-site exhaustive audiometer calibration checks and audiometric testing room background noise level checks are provided by:

  • A licensed and certified Occupational Audiologist during the annual Audiologist Plant Visit, if this service is contracted
  • A Technician for clients not receiving an Audiologist Plant Visit. For on-site services, see our website for our geographic service area: calibration services

Alternatively, audiometers can be shipped to our offices in Greensboro, NC or Indianapolis, IN for an exhaustive calibration check.  Request this service

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