Abstract: In the paper, we discuss the interference of two sound waves engendered by static sound sources in the uniform motion medium, calculate the time distance of the equiphase waves simultaneously engendered by the two sound sources to a point. It is multiplied by the pulsatance to obtain the phase difference, then we get the equation of equiphase point. Finally, we discuss the interferences in several special positions and illustrate related applications.

Key words: sound wave interference, moving medium, phase difference, longitudinal wave, velocity measurement