Segmented swept sine technique for room impulse response estimation

Abstract

The swept sine technique is very popular for the measurement of room impulse response due to its large signal-to-noise ratio (SNR) and immunity against subtle time-variance and nonlinearity of the room under test. However, the acoustical measurements in the presence of high background noise levels leads usually to unsatisfactory results. For situations of high level nonstationary noise, the mean square of the overall sequence must be minimized in order to increase the SNR. The new technique named segmented swept sine consists in exciting the room with a set of M swept sine signals with application of a dedicated weighting average method and a noise pattern recognition procedure. Each swept sine signal is segmented followed by the estimation of the mean square (MS) value of the respective segment. A weighting procedure is applied to each segment according to the MS value and the likelihood between them. The average technique is then applied. This procedure ensures that the resulting swept sine signal has the highest SNR value. Several examples are presented to compare the standard swept sine and the segmented swept sine techniques, giving advantages and disadvantages of each technique.