STUDY ON LOCAL ACTIVE NOISE CONTROL WITHIN A SMALL SEMI ENCLOSED SPACE

摘要

Previous studies on local active noise control usually focused on the cases where the control sound field could be viewed as a fully free field. This paper carried out a study on local active noise control within a small semi-enclosed space where both the direct sound and the reflected sound of the control source exist. A numerical model is established to calculate the control sound field created in such a space using the boundary element method, and a theoretical model is developed to predict the spatial extents of the quiet zones. Results showed that the control sound field created in a small semi-enclosed space is more like a partially diffuse sound field than a fully free or fully diffuse sound field, and the diffuse sound of the control source may help for local ANC to create quiet zones with more profitable spatial extension. A simple experiment is carried out and verifies the results.