A method of measuring the phase difference between probe channels for a p-p probe

摘要

This paper reports a method of measuring the phase difference between probe channels for a p-p probe. The p-p probe is a sensor for measuring sound intensity and consists of a pair of microphones closely set by face to face. In order to measure sound power level according to the method of ISO 9614-2, the sound intensity instrument which is stated in IEC 61043 has to be used. Furthermore IEC 61043 requires to evaluate the phase difference of the instrument before starting the measurement of sound power level by using it. A residual intensity testing device is generally used for a purpose of the measurement of the phase difference of the p-p probe. The residual intensity testing device normally has a little bit phase difference in itself. Therefore some bias error is caused by the phase difference of the testing device when the evaluation of a p-p probe is executed by using it. This report shows an improved method of the check for a p-p probe phase difference by two times measurements and a calculation. The method can prevent the bias error of the residual intensity testing device.