Advanced speech quality testing of modern telecommunication equipment: An overview

Modern telecommunication equipment differs quite significantly from equipment used in the past. While in traditional networks the behaviour of each transmission channel was deterministic, modern transmission systems may behave nonlinear and time variant even during a call. Signal processing is used extensively, mostly at the end points of a connection. The impairments introduced by the transmission systems and by the signal processing used are time variant as well and need to be investigated under different conversational conditions and by simulating different network and environmental conditions. The paper gives an overview about simulation and testing techniques to be used for telecommunication equipment. The impact of different network conditions and the acoustical environment on speech quality is discussed and appropriate testing techniques for evaluating speech quality under different conversational aspects are described.