SPEAKER INSTALLING DEVICE FOR SILENCING OF ACTIVE NOISE CONTROL SYSTEM

摘要

PURPOSE: To avert sound wave interference and to improve a silencing effect by providing a duct wall surface facing a speaker for silencing which generates sound waves for silencing with a sound absorbing material. ;CONSTITUTION: The speaker 3 for silencing which generates sound waves for silencing is disposed in the aperture 20 of the wall surface of the duct 1 so as to radiate the sound waves 22 for silencing in the duct 1. The wall surface of the duct 1 facing the speaker 3 is provided with the sound absorbing material 21. The sound waves 22 for silencing radiated from the speaker 3 for silencing are absorbed by the sound absorbing material 21 according to such constitution and, therefore, the sound waves returning to the speaker 3 for silencing after reflection are decreased. Then, the sound wave interference generated between the wall surface installed with the speaker 3 for silencing and the wall surface of the duct 1 facing the wall surface is averted and the sound waves having the same frequency characteristic as the frequency characteristic of the signal for silencing are radiated in the duct 1.;COPYRIGHT: (C)1995,JPO