ABSTRACT
Because there are no certified facilities for the calibration of audiometers, it may be difficult to find competent laboratories nearby. Even the audiometer distributor may not be competent in repair or calibration procedures. When a service and calibration facility is located, some understanding should be reached about the kind of calibration to be performed. Determine that hearing level accuracy will be checked for each test tone at each 5-dB interval throughout the operating range. For industrial applications the range should cover hearing levels from l 0 to 70 dB re ANSI S.6-l989 and at least test tones of 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz. Calibration specifications include tolerance limits on attenuator linearity, test tone accuracy and purity, tone presenter operation, masking noise, and the effects of power supply variations. It is always good practice to require a written report that includes all measurement data. A simple statement that the audiometer meets ANSI specifications should not be accepted without some evidence that all tests have been made. Electronic-acoustical calibration should be conducted routinely on an annual basis.
