New methods for voice quality evaluation for IP networks

The need to evaluate voice quality in VoIP (Voice over IP) applications is an important requirement for technical and commercial reasons. This may involve subjective and/or objective voice quality measurements, but existing methods may not always be appropriate for VoIP applications. The aims of the study reported in the paper are to investigate new subjective and objective measurement methods for VoIP applications. The contributions of the paper are two-fold. First, we present a new subjective, Internet-based MOS (Mean Opinion Score) test methodology which allows rapid assessment of voice quality. We conducted MOS tests using the new method as well as traditional MOS tests under different VoIP network conditions and compared the results using objective measurement methods. Preliminary results show that the Internet-based MOS test compares well with traditional MOS test (correlation coefficients of 0.95). Second, we propose novel conversational intrusive and non-intrusive speech quality measurement methods, based on the ITU PESQ and E-model to extend the applicability of existing methods. We illustrate the application of the novel approach to the derivation of model parameters for a new codec for VoIP applications (the AMR codec).