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\title{Navigating Soundspace:\\
Modelling the Sound Domain At Real World}

\author{Mark A. Simos\\
       Organon Motives\\
       45 Shea Road\\
       Cambridge, MA 02140\\
       simos@hpcesra.ce.hp.com\\
        \\
       Real World (Studios) Ltd.\\
       Box Mill, Box\\
       Wiltshire UK SN14 9PL}

\date{}
\maketitle

\begin{abstract}

This paper described a project initiated by the author in collaboration
with Real World Studios,
that is exploring ways of applying software reuse concepts,
methods and tools to the domain of synthesized and sampled sound artifacts. 
The paper provides
background on the project, motivates the applicability of software reuse
concepts and tools in multimedia domains, describes overall project aims from
a reuse perspective, and summarizes current project status.
Digital sound resources exemplify a growing
class of multimedia artifacts (such as fonts, clip art, and
video images) that challenge our conventional notions of 
software systems or modules, yet exhibit a number of ``software-like''
attributes. 
As collections
of these artifacts 
grow larger, more
complex, heterogenous and semantically rich 
we encounter problems of component
classification, retrieval, configuration and generation strikingly similar to
those addressed by software reuse research. 
Reuse techniques may therefore contribute unique approaches within the
area of audio and other 
multimedia database technology. In addition,
we expect to extend and generalize 
reuse methods and tools by applying them beyond traditional software 
domains; for example, widening our
repertoire of domain modelling techniques and representations.
Even initial inventory and modelling tasks
have yielded important general lessons for domain analysis methods. 
The project will also explore the possible role of multimedia technology 
itself as a component of general-purpose library interfaces. 

\vspace{0.3in}
\noindent
{\bf Keywords:} Domain Analysis, Reusability, Multimedia, Domain Modelling\\
\end{abstract}

\section{Background (Problem Under Investigation)}
Real World Studios is a world-class recording studio in Wiltshire,
UK, founded by Peter Gabriel in 1987, and well-known in the music industry.
A successful commercial studio, Real World's
design, architecture and organization reflect its original
intent: to create an ideal environment for recording live traditional music
performances and, more generally, to foster creative collaboration between
artists and technologists from many cultures. Real World is in fact a
``community of enterprises'', with formal or informal relations between several
businesses situated in close proximity to the studio proper, including: WOMAD,
a non-profit group that organizes international world music festivals in
Europe, Canada, and Japan; Peter Gabriel, Ltd.,
Real World Records, a joint venture record
label/publishing company; Real World Design, an engineering company that
designs and prototypes audio hardware designs; a video editing company; and a
local computer music composer-in-residence.
\par
For several years, studio engineers and musicians have struggled to organize
Real World's extensive and ever-expanding
holdings of sound material (including many unique
recordings of musicians from African, Asian, and other non-Western musical
traditions) into a library that can be more effectively accessed. 
The studio is a technologically sophisticated environment; 
while there is an immediate problem to be addressed,    
artists and engineers have given considerable thought to 
advanced technology issues involved in creating a library 
system that will intelligently augment (rather than supplant)
the current reliance on informal, intuitive, memory-based retrieval strategies.
\section{Project Aims and Approach}
The current project is
an attempt to create synergy between the studio's needs and vision and the
tools, methods and open research questions in the reuse field.
Initiating the project involved a lengthy ``warming up'' process, including
extensive and mutual education on software reuse and domain analysis concepts
and how they could be applied to the sound modelling problem, and on the
nature of the work at Real World and the studio's concept of the potential
sound library system. 
As a result, Real World has supported some initial inventory, tool development
and domain analysis activity.
In addition,
under the auspices of the studio, and as affiliate research scientist with the
Palo Alto-based Institute for Research on Learning, I am preparing a concepts
document (or ``Manifesto'') integrating Real World's conception with my previous
and parallel work in reuse ([SIMOS86, SIMOS88, SIMOS90b, SIMOS91]). 
Sun Microsystems'
Multimedia Platform Products group is contributing additional support for the
proposal effort. The Manifesto will serve as the foundation for a more
extensive project proposal; the intent is to fund the overall project with a
combination of grants from corporate, academic, and possibly governmental
(U.S., U.K. and/or EC) sources. Extracts from the library and software tools
developed may also be
productized for the commercial music market or for educational purposes.
As the following sections will make clear, we intend to pioneer innovative
approaches to domain analysis, domain modelling, and library navigation that
should contribute significantly, not only to the state of the art in the
computer music industry, but to reuse technology in general.
\par
\subsection{Reuse in Multimedia Domains.}
The domain of synthesized and sampled sound seems to fall outside the scope
of the kind of software components addressed by reuse research. In fact,
digital sound resources 
exemplify a broad class of multimedia artifacts such as font and clip art
libraries, stackware, video libraries, and animation, emerging as a natural
by-product of the computer as a digital medium. 
Since
collections of these artifacts can be stored, copied and transformed as
digital data, in managing these collections we confront classic reuse problems
such as: proliferation of subtle and unmanaged variants; 
the need for semantically expressive classification schemes; 
and the interplay of static
parts with a large repertoire of generative and transformational capabilities
[SIMOS90a].
One
objective of the project is therefore to stress techniques and tools
developed for software reuse in a multimedia information domain.
This research
should help recast these techniques and tools in more general form, and refine
our understanding of their range of application (i.e., ``re-engineering for
reuse'' our reuse research).
\par
For example, a distinguishing feature of the software reuse problem involves 
the
ability to use both constructive and generative techniques in engineering
a component. A desired program family might be implemented with a set of
static variants, with a generator, or a hybrid solution, depending on features
such as the binding-time characteristics of the implementation language.
This duality of static vs. dynamic implementation is relevant in the
digital sound domain as well: synthesizers and samplers have numerous
capabilities for dynamically altering the envelope and other attributes of
a sound resource, and to store this dynamically modified version as a separate
entity. Domain modelling tools need to provide transparent access to variants
obtained through static selection or dynamic operations on components.
\par
\subsection{Alternative Modelling Techniques}
A second, related objective of the research
is to explore ethnographic methods of data acquisition and
alternative domain modelling techniques for reuse. Software
reuse researchers have considered a wide spectrum of representation/retrieval
schemes (e.g., free text searches, keyword-in-context, faceted schemes 
[Prieto87],
entity-relationship models, semantic network, frame-based, and object-oriented
systems). While these vary widely in terms of flexibility, formality and
extensibility, most share the characteristic of being textual/verbal in nature
(even when a graphic interface is provided to navigate through the
taxonomy). Effective retrieval of multi-media information may need to rely on
different kinds of models and navigation strategies---both using different
kinds of linguistic cues and non-verbal cues as well.
Certain ``virtuoso'' studio engineers and sound
programmers are surprisingly skillful at accessing massive collections of
sound samples with minimal tool support. By empirical study of their intuitive
classification and retrieval techniques, we hope to gain important insights
into effective navigation strategies that will prove relevant beyond 
multimedia domains.
\par
For example, in a ``spatial'' model, navigation
through the component collection is projected into movement (continuous or
quantized) through a qualitative ``space'', each dimension or axis of which is
mapped to some parameter or polarity between features. As a familiar example
in the typeface domain, movement from ``light'', through ``medium'', ``demi-bold'',
and ``bold'' faces to ``extra-bold'' could be modelled as movement along an axis
of ``font weight''.
Preliminary analysis of the kinds of categories used in the
sound domain suggest that qualitative polarities like ``fat-thin'' and
``warm-cool'' may be important ways of structuring the sound palette. An
attribute of ``brightness'' vs. ``darkness'' (or ``fatness'' vs.  ``thinness'') might
be associated with one axis of the sound (or timbre) space. 
\footnote{This work
correlates in interesting ways with the notion of a ``design space'' in
software design [Lane90, Bell71]. Open research questions involve exploration
of what
reasonable measures for distance or neighborhood there may be in
different domain spaces that potentially exhibit different geometries or even
topologies.}
\subsection{Domain Modelling as Composition}
Many researchers in music perception and cognition have explored
spatial models for the perception of musical sound quality (timbre).
Most have
hypothesized a general timbre space model,
attempting to 
correlate (and validate experimentally)
specific parametric changes with intuitive, qualitative categories,
and embodying these schemes in the interfaces to 
computer music-based software systems. 
In contrast, our approach will not rely on
pre-determining a single classification scheme for the sound assets; 
rather, we see
the sound modelling system itself as a testbed supporting research into these
questions.
Our intent is to create a software platform enabling performers,
composers, engineers and listeners to iteratively evolve their own models of
the sound domain through working (and playing) with the system. We assume that
the sound model will be actively shaped to reflect individual, stylistic and
cultural preferences, and will metamorphose over time, in part through use of
the technology itself. We intend to study both the modelling and retrieval
process among a selected set of expert sound librarians, and document the
changing process resulting from use of various iterations of the toolset as it
develops. This will yield insights on how domain models develop and evolve
over time, both through the work of individuals and through joint use within
``communities of practice''. In the long term, we hope to create an environment
that encourages musicians and engineers to treat model-building as a kind of
``instrument-building'', extending and interwoven with composition and
performance.
\subsection{Use of Multimedia Information in Library Navigation.}
The software platform
must support a variety of modalities and strategies for organizing,
classifying, and retrieving sounds within the collection. The ability to
audition sounds in real time as part of active library browsing 
will be crucial to the tool's long-term success as an intuitive aid. We will
investigate where names, categories, and unorthodox linguistic strategies
can help structure the sound model, and
where auditory information itself can provide 
feedback to the
navigation process.
\par
In exploring this set of capabilities for the sound library, we will also be
considering the role that auditory cues can play in the general task of
navigating large and conceptually complex information bases. Since humans
process information differently in auditory, visual, and other sensory modes,
we may find that sound can be an important facet of any intuitive,
instrument-like, ``playable'' interface to a large library. At the same time,
musicians often use imagery drawn from other sensory modes---not only visual
terms (e.g., color associations) but terms invoking taste, smell and
temperature. It may be that intuitive, ``instrumental'' access to any collection
structured with reference to a given sensory mode relies on synaesthetic
``mappings'' to other sensory modes. If this thesis is substantiated, we
envision linkage to further domain analysis experiments in other multimedia
domains, simultaneously exploring the organization of multimedia in
libraries and its role in library interfaces.
\section{Current Status and Experience}
The first phase of the project, currently underway, involves several distinct
tasks. First, preparatory work has been done similar in many ways to the
preparation one would do for ethnographic fieldwork. This preparatory
fieldwork involved familiarization with studio personnel and the rhythms
and culture of the studio environment through interviews, documentation of
artifacts and physical characteristics of the workplace, both passive and
participant observation, and education in the complex technical
areas involved, such as comparative study of synthesizer and sampler
architectures, digital audio processing and multi-track recording technology.
It has been important to develop the project concept in collaboration with
members of the Real World community as a whole. This collaborative design
approach helps create a sense of ownership on the part of eventual users of
the system that is vital to its adoption.
\par
Partly in keeping with this collaborative notion, and partly to get something
practical done as a first step, short-term development tasks were identified
to provide some immediate benefits to the studio while examining in more depth
some of the larger issues involved. This short-term work has had three main
facets: 1) definition and implementation of a relational database system for
tracking synthesizer patches and samples from the various pieces of hardware
in the studio; 2) inventory and data collection, logging the actual sound
materials themselves; and 3) initial domain modelling: documenting the
existing, ad hoc classification system; analyzing, re-clustering and
consolidating existing categories; and finding intuitive representations for
these revised categories and their inter-relationships. 
\section{Issues}
These preliminary
stages of the project---beginning an inventory of the current, ad hoc sound
collection, assessing patterns of usage, and design of a simple relational
database---have
yielded valuable and practical insights into domain analysis and library
retrieval issues. 
It's quite useful to start with a simple
approach, even to see where it proves inadequate.
This approach is
in keeping with Prieto-Diaz' sound recommendations for an ``Initiation'' phase in
getting a reuse program established within an organization [Prieto90]. 
\par
Perhaps most illuminating have been the unexpected complexities of even
the ``simple'' inventory task.
``Software'', understood loosely as data stored in a digital medium, breaks
down our notions of physical commodities, because it can
be replicated ad infinitum with a simple copy command.
On a practical note, this means that inventorying existing assets in a
software environment may present formidable problems in sorting out true
variant versions from different copies of the ``same'' piece of software. 
For example, in cataloguing sounds on the KORG WaveStation, I found that 
approximately one third of the inventory
consisted of duplicate or multiple copies. There are many and varied
reasons for copying sounds
in the studio environment: touring disks, 
temporary ``palettes'' created for composition, or ``fly-in''
recordings for sessions.
The problem is aggravated by copies that have been ``tweaked'' at a level
of granularity far below their overall size (like two giants differing by
a toenail).
Duplication and redundancy can also be the result of
automated system activity: some
locations were filled with automatic loads from other banks within the
machine; 
in addition, some seeming
inventory was in fact empty (though misleadingly titled ``Unnamed''!)---an
``artifact'' of the hardware. All these variants must be catalogued and
sifted through in order to isolate the
library assets proper. 
These sorts of problems apply to more than the
artifacts themselves. One machine that provided an on-line database with
user-definable categories sabotaged most advantages of the category field,
simply by neglecting to provide a way of viewing the list of categories
themselves; this resulted in many spurious variants of category names, making
the database extremely error-prone to use.  Similar issues are likely to arise
in any software inventory activity.
\section{Summary}
The Real World Sound Modelling project is a novel application of reuse methods
and techniques, exemplifying a broad class of multimedia database/library
applications which may well become important new software ``media'' in their own
right. By bringing together the perspectives of multiple disciplines, we hope
to bring a more methodical approach to the structuring of sound libraries.
At the same time, by viewing domain modelling as
art form as well as engineering discipline [ARANGO89], we hope to 
bring a different
approach to conventional software domains as well---taking one semi-tone
step towards the transformation of
merely ``workable'' into ``playable'' systems.
\begin{thebibliography}{XXXXXXXXX}
\bibitem[ARANGO89]{ARANGO89} Arango, G., ``Domain Analysis-\ From Art Form
to Engineering Discipline'', in {\em Proceedings}, 5th International Workshop
on Software Specifications and Design, 1989, pp. 152--159.
\bibitem[BELL71]{Bell71} Bell, C.G., and Allan Newell, 
{\em Computer Structures: Readings
and Examples}, McGraw-Hill, New York, 1971.
\bibitem[LANE90]{Lane90} Lane, T. {\em User Interface Software Structures},     CMU-CS-90-101,
doctoral thesis, Carnegie Mellon University, 1990.
\bibitem[PRIETO87]{PRIETO87} Ruben Prieto-Diaz, ``Domain Analysis For
Reusability'', {\em Proceedings}, COMPSAC'87, 1987, pp. 23--29.
\bibitem[PRIETO91]{PRIETO91} Ruben Prieto-Diaz, ``Making Software Reuse
Work: An Implementation Model'', position paper, First International
Workshop on Software Reusability, Dortmund Germany, 1991.
\bibitem[SIMOS86]{Simos86} Simos, M., {\em Alternative Technologies for Software
Reusability}, Proceedings, 3rd STARS Workshop on Applications Systems and
Reusability, March 1986.
\bibitem[SIMOS88]{Simos88} ibid., 
``The Domain Life Cycle: Steps Toward A Unified Paradigm
for Software Reusability'', {\em Proceedings}, RMISE Workshop on Software Reuse,
Boulder, CO., October 1987; reprinted in 
{\em Software Reuse: Emerging Technology},
IEEE Tutorial, ed. Will Tracz, 1988.
\bibitem[SIMOS90a]{Simos90a} ibid., ``Methods and Tools for Reuse: Domain Analysis Issues'',
position paper, 3rd Annual Workshop on Methods and Tools for Reuse, Syracuse,
NY, 1990.
\bibitem[SIMOS90b]{SIMOS90} ibid., {\em Alternative Approaches To Domain
Analysis: Steps Toward A Job Description}, course notes, 1990.
\bibitem[SIMOS91]{Simos91} ibid., ``The Growing of an Organon: A Hybrid 
Knowledge-Based Technology and Methodology for Software Reuse'', in 
{\em Domain 
Analysis and Software
System Modeling}, ed. Prieto-Diaz \& Arango, IEEE Computer Society Press
Tutorial, 1991, pp. 204-221.
\end{thebibliography}
\end{document}

