Proper location of the transducers for an active noise barrier

The main intention of this study is to propose general criteria for the locations of the control sources and error microphones that improve the performance of the active noise barrier. Based on the proposed criteria of this study, the greater reduction is attained when the diffracted field of the noise source is canceled with the diffracted field of the control sources, that is, it is suggested to locate the control sources on the incident side and below the path that connects the furthest point in the shadow zone to the edge of the barrier. Furthermore, it is suggested that the error microphones are most suitably placed on the shadow side of the barrier where they are under the diffracted field of both the primary and control sources. The results also show that with these general criteria, the active noise control achieves an extra reduction that varies from 14.9 to 3.9 dB (for the one-third octave bands from 63 Hz to 1 kHz) and 9.3 dB for the broadband noises.