Sounds are often the result of motions of virtual objects in a virtual environment. Therefore, sounds and the motions that caused them should be treated in an integrated way. When sounds and motions do not have the proper correspondence, the resultant confusion can lessen the effects of each. In this paper, we present an integrated system for modeling, synchronizing, and rendering sounds for virtual environments. The key idea of the system is the use of a functional representation of sounds, called timbre trees. This representation is used to model sounds that are parameterizable. These parameters can then be mapped to the parameters associated with the motions of objects in the environment. This mapping allows the correspondence of motions and sounds in the environment. Representing arbitrary sounds using timbre trees is a difficult process that we do not address in this paper. We describe approaches for creating some timbre trees including the use of genetic algorithms. Rendering the...

: Aura is a new sound synthesis system designed for portability and flexibility. Aura is designed to be used with W, a real-time object system. W provides asynchronous, priority-based scheduling, supporting a mix of control, signal, and user interface processing. Important features of Aura are its design for efficient synthesis, dynamic instantiation, and synthesis reconfiguration. operating system) and systems that provide high 1. Introduction performance computer graphics rendering for Software sound synthesis offers many benefits, animation in multimedia performances. [Dannenberg including the flexibility to use a variety of 93] This requires hardware support and the algorithms, integration with control software and availability of device drivers. computer interfaces, and compact, portable hardware in the form of laptop computers. At present, software Flexibility is one of the main attractions of software synthesis is limited by processor speed (and in many synthesis, so our goal ...

This paper begins with some of the topics and questions about music improvisation using computers, the author has posed himself during more than a decade experience as a performer, composer, software designer and educator. After a quick review of several of his previous interactive music systems, some of those issues are then confronted in FMOL, a program initially designed as a tool for on-line collaborative composition that has been used by hundreds of on-line composers, and which is also being employed by the author in free-form audiovisual improvisation concerts . 1

In analyzing abstract data sets, it is useful to represent them in several alternative formats, each format bringing out different aspects of the data. While most work in data mapping has focused on visual representations, we have found that sonic representations can also be effective aids in interpreting complex data, especially when sonification is used in conjunction with visualization. We have developed prototypes for several high-level sonification tools that can be applied to a wide variety of data. While we used programmable multi-processor digital signal processing hardware to develop and experiment with these prototypes, each of these tools could be implemented as special-purpose hardware or software for use by scientists in specific applications. Our prototype tools include: Mapper (maps data to various sonic parameters), Comparator (feeds a different mapping into each speaker channel), Sonic Histogram (maps the magnitude of each category onto the amplitude of its associated...

This article will discuss the technology of SWSS and then present and compare these three systems. It is divided into three parts; the first introduces SWSS in terms of progressive examples. Part two compares the three systems using the same two instrument/score examples written in each of them. The final section presents informal benchmark tests of the systems run on two different hardware platforms---a Sun Microsystems SPARCstation-2 IPX and a Next Computer Inc. TurboCube machine---and subjective comments on various features of the languages and programming environments of state-of-the-art SWSS software. This author's connection with this topic is that of extensive experience with several different SWSS systems over the last 15 years, starting with MUS10 and including all three compared here: Csound (in the form of Music-11 initially) at the CMRS studio in Salzburg (Pope 1982); cmusic in the CARL environment at PCS/Cadmus computers in Munich (Pope 1986); and more recently a combination of cmix, Csound, and various vocoder software packages with user interfaces written in Smalltalk-80 at the CCRMA Center for Computer Research in Music and Acoustics at Stanford University (Pope 1992).

We represent sound signals as general functional compositions, called "Timbre Trees". Externally these are LISP-like expressions, internally they are implemented as C++ data structures. Nodes of the tree can be arithmetic operations, analytic functions or noise generators. Vectorized operations are provided for compact expression of additive spectral synthesis, and convolution operators for modeling acoustical environment (reverberation) within the same structure. A similar script language is also used to define three-dimensional animated motion. Simulation determines collisions and other sound-causing interactions between objects, and generates timbre trees from which exactly synchronized soundtracks can be prepared. Heuristic physically-based vibration models are used to determine the timbre of simulated instruments. Because it is often difficult to find the right composition of functions and their parameters that make up a desirable sound, we use genetic algorithms to mutate timbre trees and allow the user to guide their evolution. Time-variable parameters allow continuous metamorphosis between geometric objects and their sounds. Using this methodology, we have produced a variety of convincing animated scenes.

Nyquist is an advanced functional language for sound synthesis and composition. One of the goals of Nyquist is to achieve efficiency comparable to more conventional Music N synthesis languages such as Csound (Vercoe 1986). Efficiency can be measured in space and time, and both are important: digital audio takes enormous amounts of memory, and sound synthesis programs are computationally intensive. The efficiency requirement interacts with various language features, leading to a rather elaborate representation for signals. I will show how this representation supports Nyquist semantics in a space and timeefficient manner. Among the features of the representation are incremental computation, dynamic storage allocation and reclamation, dynamic instantiation of new signals, representation of infinite sounds, and support for multi-channel, multi-sample-rate signals.

Many recent computer applications seek to support or even participate in structured collaborations with humans. Examples range from computer-supported collaborative work to interactive music systems. This thesis presents a general model for structured collaboration based on conversational turn-taking. According to the model, collaboration participants share both a representation of the collaboration's structure and the algorithms governing navigation through that structure. ImprovisationBuilder, an object-oriented framework written in Smalltalk-80, supports this model for musical improvisation. The framework demonstrates how computers can participate in musical improvisation, and how the study of conversation can improve that participation. Two musical improvisational domains are described. The first is a free-form three part canon defined by Sal Martirano's Sound and Logic system. The second is the tradition of small jazz ensemble performance made popular in the 1940's and 50's. Impro...

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The Siren system is a general-purpose music composition and production framework integrated with Squeak Smalltalk (1); it is a Smalltalk class library of about 320 classes (about 5000 methods) for building various music-and sound-related applications. Siren can be used on all Squeak platforms