A non-linear technique for room impulse response estimation

Tim Collins
DAFx-2003 - London
Most techniques used to estimate the transfer function (or impulse response) of an acoustical space operate along similar principles. A known, broadband signal is transmitted at one point in the room whilst being simultaneously recorded at another. A matched-filter is then used to compress the energy in the transmission waveform in time, forming an approximate impulse response. Finally, equalisation filtering is used to remove any colouration and phase distortion caused by the non-uniform energy-spectrum of the transmission and/or the non-ideal response of the loudspeaker/microphone combination. In this paper, the limitations of this conventional technique will be highlighted, especially when using low-cost equipment. An alternative, non-linear deconvolution technique is proposed which will be shown to give superior performance when using non-ideal equipment.