Tutorials > Dynamic signal analysis tutorials > Sound level

Microphones can be calibrated in two ways. First, we have to know that the direct value of measurement from the microphone is the sound level in Pa. Therefore, we need to scale it to the physical quantity.

Scaling with calibration certificate

If we don't use the calibrator, but have the sensitivity of microphones, we can define it directly in the channel setup.

First, Pa is defined as the physical Unit of measurement. Next, we go to Scaling by function, check the Sensitivity and enter the value in V/Pa , which can be found on the calibration certificate of the microphone.

Channel setup for channel n

Calibrating the microphone with calibrator

Another way is to calibrate the microphone with the calibrator. In this case, the known parameter is the sound level emitted by the calibrator.
In our case it is 94 dB.

This value is entered directly in the Reference value field of the sound level module channel setup. Then we connect the calibrator to the microphone, and turn it on. We can see the signal directly in the small overview. In our case, it should be a sine wave with a frequency of 1000 Hz. Since all the frequency weighted curves are referenced to 1000 Hz, this is a very usual frequency for calibrating microphones.

NOTE	We need to use a setup sample rate in DEWESoft of at least 5 kHz or more to make a successful sound calibration. This can, however, be changed in DEWESoft Tuner.

After we see that the sound is correctly recognized as the sine wave at 1000 Hz, we can click the Calibrate button to perform a calibration. The sound module will calculate the sensitivity of microphone from the highest FFT amplitude and reference value.

The sensitivity will already be directly corrected in the source channel and therefore no additional analog scaling is necessary. We can directly check the calibrated sensitivity with the information found on the calibration certificate.