Inverse control of room acoustics using multiple loudspeakers and/Or microphones

A novel theorem is proposed for realizing exact inverse-control of a linear finite-impulse-response (FIR) system. It is named the multiple-input/output inverse theorem (MINT). It is impossible to realize exact inverse-control of a nonminimum-phase system with previously reported methods. However, even in such a case, inverse-control can be realized by using the MINT. According to this theorem, the exact inverse is constructed from multiple FIR filters (transversal filters) by setting extra signal-transmission channels to the linear system. The coefficients of these FIR filters can be computed by the well-known rules of matrix algebra. The MINT can be applied to room acoustics by using multiple loudspeakers or microphones. An experiment is made for realizing inverse-control in a sound-field. It is ascertained that The MINT is grately superior to previous methods which use only one signal-transmission channel.