communication Commercial videoconferencing products have begun to reach a level of quality acceptable for many lowintensity interactions. However, these systems fail to deliver true “high-fidelity ” that serves as a viable alternative to physical co-presence for more demanding interactions. The solution, we believe, lies in the synergy between high bandwidth networks and the application of information technologies that take advantage of such networks. Specifically, computation can be employed to enrich the communication channel, exploiting an awareness of users’ activity in order to better support their needs. In this manner, we are entering an era of communication in which distance need no longer dictate limitations on high quality distributed experiences and interaction. 1

The conditions of networked ensemble performance were simulated in an experiment. Pairs of musicians were placed apart in isolated rooms and given a simple rhythm to clap together. A microphone was placed as close as possible to each performer’s hands. Each monitored the other’s sound via headphones, and a delay was introduced between the source and listener. Starting tempo, given by a recorded count-in, and delay time were varied across trials. Recordings of the trials were analyzed with a precise event detection algorithm to locate clap onsets, from which the tempo was inferred. The rate of deceleration increased with longer delays, while shorter delays ( 11.5 ms) produced a modest, but significant acceleration. The goal is to identify the region of delay time that is most conducive to maintaining a steady tempo. This will help to determine the necessary delay conditions to support networked musical performance (which may be over long distances or in adjoining rooms). Humans performed significantly better than a simple model of a memoryless instantaneous reaction. 1

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The native time delay of audio transmission over high speed networks is used to create musical devices to play on and with the network. Different strategies that have been part of the practice of the Net vs. Net collective— a permanent network ensemble playing exclusively over wide area digital networks—are discussed. A tool to synchronize displaced musicians visually cue the performers and the audience. It also activates synchronized musical processes. The latency is used to create delay effects and reverbs embedded on the bidirectional path using feedback delay network filters. We also present a technique to play distributed rhythmic patterns over the network that are designed to sound different—with diverging rhythmic and phase structures—on each location. 1.

This talk presents the distributed immersive performance (DIP) technologies developed at the Integrated Media Systems Center at the University of Southern California, and the DIP experiments designed to assess the quality of human interaction in these remote environments. The talk represents a summary of the enabling technologies for, and an amalgamation and interpretation of findings from, our DIP experiments over the past two years. Some of the findings have been appeared in conference proceedings. The enabling technologies include low latency audio and high definition video transmission techniques that conceal packet loss and ensure smooth playback, real time streaming and archival of multiple data streams in an Internet networking environment, and 10.2-channel immersive audio for realistic reproduction of sound. The talk will highlight our results from a series of collaborative performance experiments with the Tosheff Piano Duo, focusing on auditory delay, and discussions of its effects on musical coordination and interpretation, and the players’ assessments of their abilities to adapt to the conditions. Finally, we present and discuss ongoing work and future plans.

In recent years Computer Network-Music has increasingly captured the attention of the Computer Music Community. With the advent of Internet communication, geographical displacement amongst the participants of a computer mediated music performance achieved world wide extension. However, when established over long distance networks, this form of musical communication has a fundamental problem: network latency (or net-delay) is an impediment for real-time collaboration. From a recent study, carried out by the authors, a relation between network latency tolerance and Music Tempo was established. This result emerged from an experiment, in which simulated network latency conditions were applied to the performance of different musicians playing jazz standard tunes.

This report is our second one at the MUSICNETWORK open workshop focusing on the user experiments in the Integrated Media Systems Center’s Distributed Immersive Performance (DIP) Project. The DIP project explores the creation of a seamless environment for remote and synchronous musical collaboration. We describe here the DIP experiments and findings since the last MUSICNETWORK open workshop. At the last workshop, we introduced the DIP project, our goals of studying the effects of auditory latency on musical ensemble and coordination, and the capture and analysis of user experiment data. We presented the first two sets of user experiments – collaborative performance with musicians facing each other and experiencing controlled auditory delay while performing movements from Poulenc’s Sonata for Piano Four-Hands. The preliminary results from these first experiments showed that the expert users felt that they could adapt to delays below 50ms. This year, we describe the next two sets of experiments, in which the first set of experiments required the players to practice performing with levels of delay around the threshold value, ranging from 40ms to 75ms. As before, our expert users are the award-winning Tosheff piano duo, Vely Stoyanova and Ilia Tosheff. Their practicing led to the creating of the next set of experiments, wherein the players requested for additional delay in the feedback of their own playing in order to hear the audience’s perspective. This additional delay in the

Analog audio needs a separate physical circuit for each channel. Each microphone in a studio or on a stage, for example, must have its own circuit back to the mixer. Routing of the signals is inflexible. Digital audio is frequently wired in a similar way to analog. Although several channels can share a single physical circuit (e.g., up to 64 with AES10), thus reducing the number of cores needed in a cable. Routing of signals is still inflexible and any change to the equipment in a location is liable to require new cabling. Networks allow much more flexibility. Any piece of equipment plugged into the network is able to communicate with any other. However, installers of audio networks need to be aware of a number of issues that affect audio signals but are not important for data networks and are not addressed by current IT networking technologies such as IP. This white paper examines these issues and provides guidance to installers and users that can help them build successful networked systems. 1