Akiyoshi Ishimori, Nobuo Tanaka, Hiroyuki Iwamoto
Nihon Kikai Gakkai Ronbunshu, C Hen/Transactions of the Japan Society of Mechanical Engineers, Part C, 79(799) 604-616, 2013 Peer-reviewed
Arguably, noise suppression via active noise control is effective only within a fraction of the noise wavelength from an error sensor location. To expand the controllable region, it is a common practice to introduce the multi-channelization of a control system or sound power control of a noise source per se. It is also true, however, that they entail the following disadvantages: the multi-channelization causes complication, destabilization and increment of the computational burden
control sound sources need placing close enough to the noise source to achieve sound power control, hence impracticable. To overcome the disadvantages mentioned above, this paper presents a global active noise control method using a parametric array loudspeaker (PAL). Driving the ultrasonic transducers comprising PAL with a proper time delay enables one to produce the wavefront of control sound similar to that of noise, thereby suppressing a noise propagation in the vicinity of the noise source, resulting in the generation of a global zone of quite. The validity of the method presented is then clarified numerically as well as experimentally. © 2013 The Japan Society of Mechanical Engineers.