Modern telecommunication relies upon a variety of devices, including phones and voice gateways, for communicating and rendering speech and audio signals. Avaya specializes in manufacturing equipment for converged telephone networks, in which traditional, digital time-division multiplex (TDM) networks are combined with emerging packet-speech networks (VoIP). To maintain voice quality in such a complex communications environment, researchers in Avaya are keenly focused on a variety of acoustical signal processing technologies areas, specifically: Microphones and microphone array design. Acoustically directional microphones are appearing in new telephony devices, some containing more than one microphone. Using signal processing, both beamforming and speech enhancement improve the speech-signal-to-noise ratio, resulting in better intelligibility and sound quality. Physical acoustic design for end-user devices. All telephones use microphones and loudspeaker transducers to communicate and render speech and audio as sound. Because these transducers, as well as the body of the phone itself, directly affect the quality of speech communications, physical acoustics are central to sound quality. Speech coding and transmission technologies. Speech is digitally encoded before transmission into the telephony network. In converged digital-packet-speech networks, speech may undergo several encodings during a call, so care must be taken to minimize degradation to speech quality. Echo control and cancellation technologies. Echo is caused by electrical signal reflection points within the telephone network as well as by acoustic echo paths (loudspeaker to microphone) in end-user devices. Because the large end-to-end delays introduced by packet-speech networks, such as wireless and VoIP networks, exacerbate the perception of echo, echo control is an active area of research and development. Speech enhancement algorithms. In converged telephony systems, the speech signal can undergo a series of transformations as it traverses the network resulting in degradations and distortions. Signal processing methods provide ways of restoring speech whose quality has degraded. Conferencing technologies. Today, people communicate frequently by teleconference. Signal processing technologies play an important role in making conferencing possible and in improving the quality of the conference experience.
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