Audio Quality and Acoustic Echo Issues for VOIP on Portable Devices

The control of the overall quality of service for VOIP applications depends for sure on features and capabilities of the network layer but at the same time, and especially in the case of low-resource, portable devices, it relies on smart flexible signal processing and control tools that allow tuning the usage of computational resources to obtain the best possible quality for a given system. Audio signal I/O (acquisition and rendering), packet loss concealment and acoustic echo detection and suppression play a fundamental role, since good algorithms are rather demanding for calculations but their presence is often necessary to compensate low-cost, average-quality platforms and interfaces. Some measures and remarks on these platforms and interfaces are presented in this paper, together with a set of implemented solutions providing a remarkable improvement in the mean opinion score of a typical VOIP conversation for different families of PDAs and Smartphones.