Calibration equipment

Calibration is an essential step in every precision measurement. It establishes the relationship between the sound pressure and the electrical output of the microphone.

Calibration can be performed at either 250 Hz or at 1 kHz. Both frequencies have their advantages and disadvantages.

250 Hz is in the frequency range where the frequency response of almost all microphones is flat and will therefore give the most accurate calibration.

If, however, the microphone is used in connection with measuring equipment with weighting filters, for example a sound level meter with A-weighting, the 250 Hz signal will be attenuated by the weighting network. In this case it might be advantageous to use a 1 kHz calibration frequency.

At 1 kHz, the weighting filters have 0 dB attenuation and will therefore not affect the calibration.

On the other hand, since the frequency response of the microphone is not flat, a small error could be introduced.