抄録
In general, the sound waves propagate spherically in free space, which accordingly makes the global attenuation difficult. Using ordinary loudspeaker as a control source may cause interfered sound field with both attenuated and amplified regions. On the other hand, the recent development of high-directional loudspeakers based on new sound production theory known as 'parametric array' has allowed sound transmission within a narrow range of acoustic space. In the present paper, a numerical model of parametric array based on the quasi-linear approach of Westervelt is studied, and the calculated results are compared with the measured fields. The spherically spreading noise in space is mitigated either by a normal or a parametric loudspeaker as control source, and it is known that the suggested ANC system can mitigate sound locally but cause less influence on circumferential field.
