Warped-TSP: An acoustic measurement signal robust to background noise and harmonic distortion

Abstract

TSP (Time-Stretched Pulse, lin-TSP afterwards) and logarithmic TSP (log-TSP) are commonly used in impulse response measurements of audio systems and room acoustics. But the optimal test signal for each environment is different. It is necessary to choose an appropriate test signal for each environment to achieve a better SNR in the measured impulse response. A new acoustic measurement signal that is a hybrid signal of lin-TSP and log-TSP is proposed. The proposed signal, called “warped-TSP,” achieves an SNR higher than that obtained by lin-TSP and log-TSP. It also provides a means to eliminate harmonic distortion due to the reproduction system. In this paper, the definition and features of warped-TSP are introduced in comparison with lin-TSP and log-TSP. We also present the relations between the parameters of warped-TSP, the amplitude frequency characteristics of warped-TSP, and the effects on the representation components due to harmonic distortion. Based on these discussions, a method of selecting the optimal parameters of warped-TSP for a specific measuring environment is given. A series of impulse response measurements performed under different ambient noise conditions revealed that the proposed method outperformed lin-TSP and log-TSP under all conditions in terms of the SNR of the measured impulse response. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(4): 18– 26, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20260