An approach to global equalisation in a rectangular room at low frequencies

The motivation of this study is the fact that sound reproduced in a room undergoes a spectral colouration, which is undesirable. This effect is particularly severe at low frequencies in small enclosures.A theoretical study based on computer simulations is presented. The listening area is a continuous region in a rectangular room that occupies almost the entire room.

A travelling wave is generated by feeding a number of loudspeakes with the signal to be reproduced passed through digital filters. The problem of designing these filters is investigated both in the frequency domain and in the time domain. Modelling delay is used in the time domain to obtain the optimal values of the control filter coefficients in the least-square sense.

The sound field can be estimated with sensors placed closed to the walls and the ceiling.