The standard hydrophone is calibrated to convert the sound pressure on it into the AC voltage signal of the same frequency and waveform, which is proportional to the intensity of the sound pressure. When the hydrophone is inserted into the liquid medium under ultrasonic action, it has a voltage signal output. After the preamplifier is amplified without distortion, it is sent to AC voltmeter. The digital frequency meter can measure the frequency of the ultrasonic wave at the same time, and the oscilloscope can monitor the change of the signal voltage waveform at any time. This method of measurement has been widely used.
Obviously, this method is effective, but it is expensive and cumbersome. It also has high technical requirements for operators, and can not be used as a routine testing method.
Japan has made a breakthrough in the field of acoustic testing equipment. They have developed a special ultrasonic cleaning machine ultrasonic measuring instrument (UTK-30), which sets sound pressure measurement and frequency measurement in one, and can easily measure sound pressure and frequency of sound field. But the disadvantage is that the instrument is large in size and consumes more electricity, so there are many inconveniences in use.
At the end of last year, an ultrasonic measuring instrument was developed in China, which is dedicated to the measurement of such strong ultrasonic field.