Problems of signal processing in modern wireless terminals and its impact on speech quality
Ekkehard Diedrich, Hans Wilhelm Gierlich · The Journal of the Acoustical Society of America · 1999
Modern terminal applications in speech communications are more and more including signal-processing technologies, such as switching devices, echo cancellers, nonlinear processors, level control, and compander a.o. Apart from the benefits of such technologies, there are doubtless impacts on the speech transmission quality like echo, level fluctuations, and clipping. Even modern terminal developments, e.g., for mobile communications lead to shorter and compact handset designs with some negative influences on the speech transmission quality from an acoustical point of view. One example is echo because of the stronger internal coupling between microphone and loudspeaker in very short handsets and the need for echo control to avoid the negative impact on speech quality. New test and measurement procedures (subjective and objective) are described and discussed to give the possibility of classifying these impacts on speech transmission quality.