The implications of commercial 5.1 and 7.1 surround formats for computer music
sound design: an environmental approach to aesthetics and practical techniques.
Dr Ambrose Field
Director, Electroacoustic Studios
University of York, UK. YO10 5DD
aef3 @york.ac.uk
Abstract
5.1 and 7.1 are standard and popular
loudspeaker layouts, defined by the film industry
and International Technical Union (Holman,
2001). In addition, the 5.1 format has gained
considerable market ground by being available
to end-users via the DVD medium. It is the
purpose of this paper to explore practical ways
in which composers working in electroacoustic
and computer music might take advantage of
these formats, as opposed to spatialisation
methods which are often customised to the needs
of individual works, institutions and venues.
The paper recommends an integrated,
environmental approach towards mixing, and
provides basic ideas as a springboard for
composer experimentation in this growing
arena. It is important to note that the future
challenges of 5.1 and 7.1 probably do not lie in
solving engineering problems: most issues
presented here are conceptual, and concern the
compositional reasoning behind the choice of
positioning elements within in a soundfield.
Whilst it is acknowledged that 5.1 and 7.1
sound projection is relatively low-resolution
spatially, there are many compositional
opportunities afforded by commercial layouts
that should not be overlooked. This paper
examines these issues, and is accompanied by
surround audio examples on DTRS (or ADAT)
tape.
1.0 Why spatialize music?
Before attempting to define any aesthetic
considerations relating to 5.1 and 7.1
surround it is necessary to examine the need
per-se to spatialize music. Two basic ideas
lie at the root of modem spatialized music,
although their specific applications may vary
with the needs and requirements of individual
composers. These are:
i) The creation of enveloping and aurally
engaging environments, and
ii) musical choreography.
Subsidiary aims, such as allowing for greater
audience coverage and the implications of
any additional requirements of the medium
(such as the placement of dialog in the centre
speaker in film sound) are also important
considerations.
1.1 Creating new environments
Surround sound systems are particularly
adept at creating a sense of physical space in
music (Schafer, 1973:15), and multi-speaker
sound diffusion methods are often used to
provide convincing re-interpretations of
spaces, be they real or imaginary. Firstly, the
use of recorded physical spaces can lend
credibility to a compositional environment in
a way that is not possible in stereo. I have
termed this Reality credibility, which is
examined in detail in a previous publication
(Field, 2000:45). For a reproduced
environment to appear convincingly natural
(even if the end goal is a totally imaginary
space), it is beneficial to work with material
that has remained in the destination
surround-sound format from the outset.
Gibson (1966) demonstrates that
environmental cues are paramount to our
perceptual understanding of spaces.
Extending this idea to soundscapes, it is the
nature of the relationship between the sound
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