Abstract
Network conditions such as packet loss and delay jitters greatly affect the end-to-end speech quality of VoIP (Voice over IP). For this reason, it is necessary to clarify how these network conditions affect the speech quality, and to guarantee the speech quality by applying QoS (Quality of Service) management technology in network and VoIP terminals. This paper represents evaluation results of speech quality, which is measured by objective speech quality assessment "PESQ" (Perceptual Evaluation of Speech Quality) when the network conditions change. In addition to the PESQ score, this paper shows the MOS (Mean Opinion Score) which is derived from the subjective listening tests. This paper also discusses the correlation between PESQ and MOS, especially when the packet loss and delay jitters occur.
