Measurement microphone

What is a measurement microphone and what is it used for?

The measurement microphone is the heart of every acoustic room measurement. It serves as a reference to be able to determine the properties of an unknown room. Measurement microphones are always condenser pressure receivers because of the extremely good transmission properties required. Special power supplies are normally required for the power supply, which supply a very high polarization voltage (usually 200 V). In the lower price range, there are also measurement microphones with electret condenser capsules that require a lower supply voltage. Measurement microphone capsules are manufactured in four standardized diameters (inch, half inch, quarter inch, eighth inch) and offered in free-field and diffuse-field equalized variants. With the associated impedance converter, the small capsules transmit linearly up to the ultrasonic range.

Some capsules can also pick up infrasound. The measurement microphone serves as a comparison microphone for frequency response measurements.

A sound source that generates a precisely defined and reproducible sound pressure is required to calibrate the room measurement. A sine sweep is usually used for this.