An improved prototype of the “voiscape” voice communication medium has been developed and subjectively evaluated. Voiscape enables natural and seamless voice communication by using sound to create a virtual “sound room” in which people, who are represented by different sounds, can move freely. It features low-delay motion-tracking spatial audio with simulated early reflections that produce out-of-head sound localization and sound distance expression. It also features virtual-location-based selective communication: a user can walk freely in the sound room using a map- and cursor-key-based user-interface and can select whom to talk to or which sound sources to listen to. A third feature is SIP-presenceevent-notification (SIMPLE)-based sound room management: when users move, their locations and directions are distributed using SIP SUBSCRIBE/NOTIFY messages. The combination of these features creates a natural voice-communication space in which two or more parallel conversation con...