Peculiarities of Testing the Impact of Packet Loss on Voice Quality

Abstract

Some packets may be lost or corrupted when voice is transmitted using radio channel. Current voice coders use complex techniques for masking of lost segments. Thus overall speech quality is improved. This work shows experimentally that masking technique changes not only signal corresponding to lost frame, but also subsequent signal. Work investigates properties of PESQ algorithm when quality degradation is due to localized frame errors. The impact of measurement window length and position is investigated using theoretical and experimental methods. It is shown that longer measurement window artificially decreases the impact of localized frame error. Also it is shown that position of measurement window influences measured result. These experiments show high uncertainty may result from using standardized PESQ algorithm for the signals with localized errors. We propose a method for reduction of measurement uncertainty witch is based on artificially constructed voice signal and standard PESQ algorithm. Ill. 11, bibl. 10 (in English; summaries in English, Russian and Lithuanian).