Active cancellation of pressure at a point in a pure tone diffracted diffuse sound field

In this paper the extension of the average zones of quiet produced in a diffuse acoustic field is studied when the acoustic pressure is cancelled at a point near a reflecting surface by using a remote secondary source. Analytical expressions for the extension of the zones of quiet generated when the cancellation point is close or on the surface of a rigid sphere, a wall, a two-wall edge and a corner have been derived. These theoretical results are compared with simulation results for the pressure in the vicinity of the cancellation point, and show good agreement. (C) 1997 Academic Press Limited.