Black box measurement of musical tones produced by noise reduction systems

In the context of noise reduction algorithms, three instrumental measures are of major interest: the speech component quality, the level of noise attenuation, and noise distortion in terms of musical tones. As several proposals are made for the first two, the amount of musical tones is commonly still subjectively evaluated. Recent exploration of the log-kurtosis ratio for instrumentally measuring musical tones has led to white box test methodologies requiring specific information about the particular noise reduction algorithm. In this paper we propose a simple yet robust instrumental musical tones measurement, which is applicable to arbitrary unknown noise reduction systems, i.e., a black box measurement. A subjective listening test has been conducted to verify the proposed instrumental measure. Our measurement methodology has been proposed as part of an ITU-T Recommendation in Study Group 12, FG CarCOM.