3D Audio Conference System with Backward Compatible Conference Server using HRTF Synthesis

This article describes a system that is able to perform online sound localization, separation and speaker recognition for the purpose of channel assignment in teleconferencing scenarios. The assigned channels are then virtually synthesized to different positions around the listener by a conference server using Head-Related Transfer Functions (HRTFs), which enables the user to identify active speakers in an audio conference. Intelligibility of communication is also increased by making use of the cocktail party effect which describes how a user can concentrate on one specific participant, even if there are more simultaneously active speakers. To support regular telephone systems, we focus in particular on compatibility to existing Voice over IP (VoIP) infrastructure by using standardized protocols and central signal processing. Both traditional telephone devices and software clients are put into one heterogeneous conference. While the conference server transmits the down-mixed, single-channel conference signal to regular phones, the software clients can receive a stereosignal enabling full 3D audio.