A New Method for the Determination of the Acoustic Center of Acoustic Transducers

The concept of acoustic center is important in practical realization of free-field reciprocity calibration of microphones. The accuracy in the position of the acoustic center has a significant influence on the accuracy of the estimated free-field sensitivity of the microphones. The last experimental methods used for half inch microphones allows to obtain results only from 2 kHz (the current lower frequency limit). In order to broaden this frequency range (in the lowest frequency domain, from nearly 2 kHz to 400 Hz), an improved experimental method which increases the signal to noise ratio is presented here. Thus, today, experimental results, which are based on the inversely proportional distance law, are available from 400 Hz to 20 or 30 kHz.