Abstract: A device for and method of calibrating a microphone, comprising a loudspeaker (3) for converting a loudspeaker input signal (5) into sound; a microphone (4) for converting received sound into a microphone output signal (16), and calibration means for calibrating an output power of the microphone relative to a desired power level. The calibration means comprise impulse response estimating means (7) for estimating an acoustic impulse response of the microphone by correlating the microphone output signal (6) and the loudspeaker input signal (5) when the microphone (4) receives the sound from the loudspeaker (3), whereby the output power of the microphone (4) is estimated.