Quality assessment of speech enhancement systems by separation of enhanced speech, noise, and echo

Abstract

Abstract Quality assessment of speech enhancement systems is a non-trivial task, especially when (residual) noise and echo signalcomponents occur. We present a signal separation schemethat allows for a detailed analysis of unknown speech enhance-ment systems in a black box test scenario. Our approach sep-arates the speech, (residual) noise, and (residual) echo compo-nent of the speech enhancement system in the sending direc-tion (uplink direction). This makes it possible to independentlyjudge the speech degradation and the noise and echo attenua-tion/degradation. While state of the art tests always try to judgethe sending direction signal mixture, our new scheme allows amore reliable analysis in shorter time. It will be very usefulfor testing hands-free devices in practice as well as for testingspeech enhancement algorithms in research and development. Index Terms : objective signal quality assessment, non-blindsignal separation, speech enhancement, hands-free 1. Introduction In science, a comfortable way to evaluate speech enhancementalgorithms is to digitally add near-end speech and noise to theecho signal and thereby construct the microphone signal. Dur-ing the uplink processing of the speech enhancement (hands-free) system the operational influence on the noisy microphonesignal is then to be logged, and later applied individually to thespeech, echo, and noise components of the microphone signal(see, e.g., [1, 2, 3]). This presumes linear processing, as canbe found e.g. in frequency domain noise reduction, where again is applied to the spectral amplitudes. The strength of suchmethod is that one achieves three separate signals: The filteredspeechcomponent, thefilteredechocomponent, andthefilterednoise component, which represent the (slightly) distorted near-end talker’s speech signal, the suppressed echo signal, and theresidual noisesignal, respectively. Focusingonnoisereduction,e.g., aspects such as speech distortion, noise attenuation, andnoisedistortioncan thencomfortably bemeasured or auditivelyassessed.Thishowever isa