Performance measures of noise reduction algorithms in voice control channels of UAVs

In this paper, six noise reduction algorithms had been compared with the use of a set of indicators. Among them are popular noise reduction algorithms such as spectral subtraction, Wiener filtering, MMSE and logMMSE, and two less well-known Wiener-TSNR and Wiener-HRNR algorithms. It is shown that when the noise reduction system is used as preprocessor of automatic speech recognition (ASR) system, only a small amount of speech quality indicators is in satisfactory agreement with the recognition accuracy. In particular, these include Log-Likelihood Ratio (LLR) and Signal Composite Index (SCI) indicators. In addition, it is shown that there is no single algorithm among the considered noise reduction algorithms, which is the best in terms of maximum recognition accuracy for a wide range of input signal-to-noise ratio from minus 10 dB to plus 30 dB.