混响声场的有源控制

本文对室内声场的有源控制问题进行了探讨。发现直达声是指向性的,除非用同样指向性的反声源如对户外大型噪声源那样,是不能用有源控制的。但混响声场是驻波场,在屋角的次声源可以激发所有驻波(简正振动),因此可以作适当调制使其抑制整个混响声场。理论分析和初步实验证实此点,取得令人鼓舞的结果。对于须待解决的问题也进行了讨论。

Active noise control of reverberant sound

The problem of active noise control of interior sound field is investigated. It is found that the direct sound is directional and is not subjected to active noise control, excepc the application of anti-sound sources as in case of noise sources in the open. While the reverberant sound field is a field of standing waves, a secondary sound source at the corner of the room may excite all the standing waves (normal modes of vibration), and hence is suitable for the suppression of the whole reverberant sound field after being modulated approprietely. Theoretical analysis and preliminary experiment confirm this prediction and encouraging results are obtained. The existing problems are discussed.