Instrument and System Calibrations

Temperature and humidity may affect the performance of instruments in microphone and speaker tests. To avoid this, routinely calibrate instruments and the test system to ensure accuracy.

Instrument Calibration

Instrument manufacturers usually calibrate instruments on a yearly basis in accordance with ISO standards or other quality standards. Typical instruments that need to be calibrated include input and output instruments and reference microphones.

System Calibration

System calibration is particularly important for manufacturing tests, where manufacturing lines of the same type may differ without calibration.

To start system calibration, connect a DUT to the system and then perform the following operations:

  • If the DUT is a microphone:
    • Calibrate the input voltage to the speaker at a specific sound pressure.
    • Equalize the speaker to flatten the frequency response.
    • Calibrate the reference microphone sensitivity using a microphone calibrator.
  • If the DUT is a speaker:
    • Calibrate the input voltage to the DUT at a specific sound pressure (the internal or external amplifier gain needs to be considered).
    • Compensate for the frequency response of the amplifier.
    • Calibrate the reference microphone sensitivity using a microphone calibrator.