自适应空间有源消声最佳消声效果的实现

Realization of the Best Sound Attenuation in Spatial Adaptive Active Sound Control

本文针对一个自适应有源消声控制系统以及一个以点声源为次级源的声系统，就如何实现空间最佳消声效果问题进行了讨论，给出了误差传声器的个数及空间位置与空间消声效果之间的关系，提出误差传声器应放置在实现消声后声压的极小方向上。所得结论在实验中得到了证实。

In recent years,techniques of active sond control in three-dimension space have been developed rapid-ly. Especially the adoption of adaptive techniques provides an effective manner for practical use of active sound control. For an adaptive active attenuation system,the error sensor can be regarded as a monotor. The adaptive system adjusts the complex strengths of secondary sources continuously in order to keep the sound pressure at the position of error sensor minimum. In principle,if a global reduction is needed in space,a large number of error sensors distributed in space are needed. But this is unpracticable because much more error sensors may cause many questions. So it is important that how to obtain the best possible effects by using limited error sensors. Obviously,this problem is actually equivalent to selecting the best places of error sensors. This paper deals with an adaptive active control system and a acoustic system of which the secondary source is point source. The selection of the position of error sensors to get the best at-tenuation effects is discussed.Through the analyses,it can be seen that the number of error sensors should be equal to that of secondary sources at least and the error sensor should be put in the direction that the di-rectivity of optimal sound field is minimum.Because the minimum directions are usually more than the number of the secondary sources,it is found that error sensors must be put in the minimum directions which are uncorrelated each other. In experiments,one and two secondary sources are used respectively. Because of the symmetry of the primary source,only one error sensor is used.The attenuation effects are satisfied and theorectical results are verified.