Detailed comparative analysis of PESQ and VISQOL behaviour in the context of playout delay adjustments introduced by VOIP jitter buffer algorithms

The default best-effort Internet presents significant challenges for delay-sensitive applications such as VoIP. To cope with non determinism, receiver playout strategies are utilised in VoIP applications that adapt to network condition. Such strategies can be divided into two different groups, namely per-talkspurt and per-packet. The former make use of silence periods within natural speech and adapt such silences to track network conditions, thus preserving the integrity of active speech talkspurts. Examples of this approach are described in [1, 2]. Per packet strategies are different in that adjustments are made both during silence periods and during talkspurts by time-scaling of packets, a technique also known in the literature as time-warping. This approach is more effective in coping with short network delay changes because the per talkspurt approach can only adapt during recognized silences even though the duration of many delay spikes may be less than that of a talkspurt. This approach however introduces potential degradation caused by the scaling of speech packets. Examples of this approach are described in [3, 4] and such techniques are frequently deployed in popular VoIP applications such as GoogleTalk and Skype. In this research, we focus on applications that deploy per talkspurt strategies, which are commonly found in current telecommunication networks