COMPOSING FOR RELATIVE TIME IN DISTRIBUTED
PERFORMANCE
Robert Rowe
New York University
Steinhardt School
Department of Music &
Performing Arts Professions

ABSTRACT
Music is a temporal art. Recent experience with
distributed performance has introduced new challenges
to traditional ways of thinking about time with respect
to ensemble composition and performance. Performing
across two sites connected by the Internet entails
compensating for delays, though those delays have
become shorter and musicians more experienced in
dealing with them in recent years. When the number of
sites involved grows to three or more, however, another
layer of complexity is added as performers at the
various sites are confronted with different
configurations of latency, and thereby significantly
different performances, at each location.
1. INTRODUCTION
Distributed performance has been with us for many
years now [3][4]. In this paper I will discuss in
particular those performances that are distributed via the
Internet, in which one or more venues broadcast to and
receive audio and video signals from the other sites and
render these onstage as part of the performance itself. At
New York University we recently participated in a
demonstration for the Audio Engineering Society
conference of a communications protocol and
compression scheme that was able to connect musicians
in New York and McGill University in Montreal, via
audio and video signals, with under 20 milliseconds of
latency [1]. A similar demonstration between NYU and
McGill in 1999 had 1000-3000 milliseconds of latency
[5]. The difference between even 1000 and 20 ms of
latency is so profound as to constitute a different
technology altogether. Twenty milliseconds of delay is
the same as that experienced by two musicians seated
twenty feet apart. In the AES conference, a drummer in
Montreal and a bass player in New York were able to
play rhythmic material in perfect synchrony. With 1000
milliseconds of latency, such an outcome cannot even
be attempted.
2. LATENCY TOLERANCE
Transmission rates over the Internet range from a 28.8
thousand bits-per-second (bps, or baud) telephone
dialup line to the 100 million bps or more available on
high-speed broadband connections. Clearly, a 28.8k
baud telephone connection is too slow to keep up with
even the 31.25k baud bandwidth requirement of MIDI,
not to mention the 1.4 megabaud needed for stereo, CD-
quality digital audio. Even when a transmission channel
with sufficient theoretical bandwidth is used, signals
going into and coming out of the link are often buffered
to compensate for network congestion between the two
machines. Depending on the nature of the signals being
sent and the quality of the transmission channel, these
buffers may typically range anywhere from 5 to 1000
milliseconds or more.
Given that background, what degree of latency is
tolerable in a distributed performance situation? In a
recent paper titled ““Effects of time delay on ensemble
accuracy””, Chris Chafe and colleagues at Stanford
report on tests of rhythmic performance under varying
latency conditions [2]. They asked pairs of musicians
located in separate rooms but with audio shared through
headphones to clap a simple rhythm together. Increasing
delays beyond a duration that might normally be
encountered in live performance led to an eventual
breakdown in the shared rhythm. The observed behavior
was a gradual tendency toward slowing down the tempo
as delays increased, but eventually that strategy could
no longer successfully maintain the rhythm and the
performance would break down altogether. The ideal
delay for performing the rhythm in a steady tempo was
11.5 milliseconds –– with shorter latencies performers
actually tended to speed up slightly. "The observed
optimal one-way delay dbest = 11.5 ms equates with a
physical radius of 2,400 km (assuming signals traveling
at approximately 70% the speed of light and no routing
delays)" [2]. Though the ideal is 11.5 ms, the
performance falls off slowly enough to indicate the
possibility of reasonable performance up to 20 ms or so.
3. THE TECHNOPHOBE & THE MADMAN
In 2000-2001 the New York State Council on the Arts
(NYSCA) commissioned a work from New York
University, Rensselaer Polytechnic Institute, and
Harvestworks (a New York-based arts foundation) that
would be presented at NYU and RPI simultaneously,
using an Internet connection between the two sites. The
purpose of this commission (which became The
Technophobe and the Madman) was to explore the
artistic consequences of composing for the medium of
Internet2. One expression of this exploration was an
extensive rehearsal period that spanned several months