Tunable noise absorption by shunted loudspeaker

Abstract

Tunable absorption is a desirable feature in the audio room and concert halls. Mechanically, it's hard to tune the level of absorption or the effective frequencies of an absorber. This work introduces an RLC shunt circuit for a loudspeaker used as a noise absorber. When the diaphragm is pushed by incident noise, electromotive force (EMF) is generated across the coil which resists diaphragm movement and results in electrically induced mechanical impedance. The character of the induced impedance is totally different from that of conventional mechanical system. By manipulating components of the electrical circuit, system reactance can be reduced and redistributed hence the modification of random-incident sound absorption level in broadband over a large range of sound energy absorption, said 0.60.9. The device functions much like a tunable electrical filter, and the proposed absorber can also shift its resonance to frequencies of interest.