Calibration of microphoneMicrophones are available in a large number of designs with different frequency characteristics and size, depending on the environment in which they are to be used. Characteristics and calibration methods for microphones are specified in a standard series, IEC 61094, with a number of different parts.
A microphone calibration at RISE consists of the following determinations:
- Sensitivity at 250 Hz
- Frequency response
- A-weighted self-generated noise
The determination of sensitivity is made by comparison against a reference microphone while the frequency response normally is measured in a closed coupler or with an electrostatic actuator. We can also calibrate a microphone in free field, if necessary.
Mechanical damage of the microphone membrane. Small damages are the most treacherous as they cannot be seen with the naked eye and they do not have any effect on the result at 1 kHz, which in most cases is the frequency of the calibrator, but the effect can be very severe at lower frequencies.
Damp in the microphone. Often shows itself as a low-frequency interference.