Abstract: An effective method of measuring the velocity of sound in metal rods is introduced by combining the standing wave method with acoustic sensors. A metal rod is fixed at its midpoint and vibration along its length is excited by rubbing it. A longitudinal standing wave is generated in the rod and sound waves are produced in the air. The digital information system ( DIS) is used to collect the sound signal and directly to display acoustic wave forms on the screen. The velocity of sound in the metal rod is then calculated and determined by measuring the fundamental frequency of sound waves in conjunction with the wavelength. The sound velocity in four different metal materials ( including aluminum，steel，brass，and copper) is measured respectively. The experimental results showed that the sound velocity obtained by this method is consistent in the same material metal rods of different lengths. The relative error of the sound velocity between the measured values and the well-known standard values in various metal materials is less than 6.00%. One advantage of this new method is that it can turn the acoustic signal into visible waveforms.

Therefore，calculation parameters can be extracted directly and accurately from the waveforms.

Key words: sound velocity in metal, standing wave, fundamental frequency, DIS digital information system