The Very Near Field Theory, Simulations and Measurements of Sound Pressure and Particle Velocity in the Very Near Field

Abstract

In acoustics concepts like the ‘far field’ and ‘near field’ are well known. The sound field at a position much closer to the source than its typical size is introduced in this paper as the “very near field”. The boundary conditions are specified and verifying measurements are demonstrated. It is shown that in the very near field the particle velocity is frequency independent and almost independent of the distance to the source whereas the sound pressure is suppressed, frequency dependent and also almost independent of position.