Scantek Inc  //  Details on Calibration Services 2. Acoustical Calibrators and Pistonphones

2. Acoustical Calibrators and Pistonphones
 

The three main parameters (sound pressure level [SPL], frequency, and distortion) characterizing the sound produced by a calibrator are measured for every combination level/frequency implemented in the tested device. At request, we also can provide the stability parameters for SPL and frequency.
 

All tests are performed in conformance with ANSI S1.40: 2006 / IEC 60942:2003 Annex B:
 

  • The SPL is measured using a reference microphone:

    "Following coupling of the reference microphone to the sound calibrator, the time specified in the instruction manual shall be allowed for the microphone and sound calibrator to stabilize. The sound pressure level generated by the sound calibrator shall then be measured as an average over 20 s of operation, … . The measurement … shall be replicated twice, to give a total of three tests." ( IEC 60942: 2003, pg. 81)
     

  • In a similar way, the sound frequency is measured as an average over several seconds.

  • The total harmonic distortion is tested either with a distortion meter or using the analyzer method over a frequency domain from 20 Hz to 20 kHz. In both cases, the fundamental is rejected and the level of the signal composed of the remaining harmonics is compared with the global signal.