Simple Method for Measuring the Sound Velocity of a High Absorption Liquid

A new method for measuring the phase velocity at MHz frequencies is presented. Two quartz transducers are separately placed; the time difference between the ac-voltage pulse (tone burst) applied to the transmitting transducer and the out-put-voltage pulse of the receiving transducer is measured with an accuracy of several percent of the period of resonant vibration of the transducers. A special technique is used in order to find the cycle-for-cycle matching between the two pulses. The measurement is easily performed even with a liquid of 40 dB absorption between the two transducers.