Sound source directivity considering source movement

Abstract

When the source moves, frequency modulation (Doppler effect) occurs in the radiated sound, and the directivity of source changes. In addition, the source can be not located in a direction from the direction of arrival of radiated sound. Therefore, the sound pressure directivity may differ depending on whether the source is static or moving. There are two types of wave equations, one that describes sound pressure as a variable and one that describes velocity potential as a variable. When the sound source moves at a constant velocity and the equation is solved assuming that the source strength is constant with respect to the velocity, the sound pressure directivity of the radiated sound changes depending on the description method of the wave equation. The sound pressure was obtained by solving the wave equations where a single monopole source and a dipole source are moving at a constant velocity. From the results, we showed the difference of sound pressure directivity when source is moving from the directivity of static source.