Most techniques for estimating the transfer function (or impulse response) of an acoustical space with a high signal-to-noise ratio 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 transmission waveform into an approximate impulse and equalisation filtering is used to remove any colouration 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 using both synthetic waveforms and practical room measurements.
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