Improving Perceived Speech Quality of VoIP over Error-Prone Channels

The provisioning of an appropriate level of perceptual speech quality is crucial for the successful deployment of Voice over the Internet Protocol (VoIP). Today’s heterogeneous multimedia networks include links that introduce bit errors into the voice data stream. These errors are detected by the IP packet transport protocol and result in packet losses which eventually degrade the speech quality. However, modern speech coding algorithms can either conceal packet losses or tolerate corrupted packets. In this paper, we investigate to which extent it makes sense to keep corrupted speech data for the special case of uniformly distributed bit errors. We simulate different transport strategies that allow the incorporation of damaged speech data into the speech decoding process. The results from an instrumental speech quality evaluation show that keeping as much damaged data as possible leads to superior performance with regard to the perceptual speech quality compared to dropping packets and using packet loss concealment.