This issue of Organised Sound is about interactivity, a theme that the journal has often visited in the past. What makes this visit to this very important subject special is that it has been chosen as the first theme within our annual collaboration with the International Computer Music Association (ICMA). The ICMA President, Mary Simoni, has joined the Editors this year as ICMA representative and Mara Helmuth, currently the ICMA's editor of Array, has kindly taken on the role of Guest Editor for this issue. The journal Editors would like to welcome the ICMA and thank those ICMA members, and Mara in particular, who helped to make this issue possible. We look forward to further developing this collaborotion.

Pikapika is a collaborative solo performance by Bahn and Hahn that presents a simple model of composition, choreography and collaboration in an interactive context. The piece offers the possibility of a new kind of interactive theatre/costume design –an interactive sonic character. This essay is a case study of a design process for interactive performance. While we include some details of our specific interface, these are primarily employed as examples to suggest our principles for creating personal, idiosyncratic interactive systems. Our collaboration integrates elemental sound and movement relationships with an awareness of the embodied cultural knowledge of the performer and with a specific sensing scheme to capture her particular gestural vocabulary. The combination of individual ‘atoms’ of movement and sound leads to a complexity that must be practised until they can be performed with ease as an embodied interaction. We find the process of collaboration and its articulation as a dynamic interactive structure fascinating and enduring beyond the specific technologies employed. The terms meta-composition, composed instrument and composed character are used to describe the interactive structure of the piece.

In contemporary music and arts practices the previously distinct roles of author, composer and performer have become increasingly conflated, catalysed by the use of computer technology. Newly combined roles of composer and performer that are assumed by one or more people or computer systems are identified and described, as well as actions including preparation, organisation and presentation. In this paper the interface is described as an ‘interactivated space’ to encompass both the intimate scale of a performer manipulating the materials through an on-body interface, and the larger in-space interface where the work is shared with the performers and audience. Two examples of projects the authors are involved in are described, which form the basis for further discussion. The two interfaces that manifest themselves in the processes, the instrument and the score are discussed in more detail with a focus on their changed appearance and role.

In the early 1930s, maverick composer Henry Cowell collaborated with inventor Leon Theremin to build an electronic instrument capable of producing intricate polyrhythms. This instrument, dubbed the Rhythmicon, can be considered a rudimentary example of an interactive music system. Cowell and Theremin created the machine to fulfil a compositional need, but it ultimately failed to become a successful musical instrument. The Rhythmicon was one of the first electronic music instruments to use technology to extend performers' musical capacities, anticipating the interactive computer music movement by several decades. Despite its shortcomings, the Rhythmicon should be remembered as an important step on the road to interactivity.

The expression gestural mapping is well imbedded in the language of instrument designers, describing the function from interface control parameters to synthesis control parameters. This function is in most cases implicitly assumed to be instantaneous, so that at any time its output depends only on its input at that time. Here more general functions are considered, in which the output depends on the history of input, especially functions that behave like physical dynamic systems, such as a damped resonator. Acoustic instruments are rich in dynamical behaviour. Introducing dynamics at the control stage of an electronic instrument can help compensate for lack of dynamics in later non-physical synthesis stages. A broadening of the function space offers new aesthetic possibilities for composing instruments. Examples are presented to illustrate the new design/composition mode as well as practical techniques. In this context, it is suggested that the word mapping be updated with the more descriptive expression dynamic control processing.

This article collates results from a number of applications of interactive evolution as a sound designer's tool for exploring the parameter spaces of synthesis algorithms. Experiments consider reverberation algorithms, wavetable synthesis, synthesis of percussive sounds and an analytical solution of the stiff string. These projects share the property of being difficult to probe by trial and error sampling of the parameter space. Interactive evolution formed the guidance principle for what quickly proved a more effective search through the multitude of parameter settings.

The research was supported by building an interactive genetic algorithm library in the audio programming language SuperCollider. This library provided reusable code for the user interfaces and the underlying genetic algorithm itself, whilst preserving enough generality to support the framework of each individual investigation.

Whilst there is nothing new in the use of genetic algorithms in sound synthesis tasks, the experiments conducted here investigate new applications such as reverb design and an analytical stiff string model not previously encountered in the literature. Further, the focus of this work is now shifting more into algorithmic composition research, where the generative algorithms are less clear-cut than those of these experiments. Lessons learned from the deployment of interactive evolution in sound design problems are very useful as a reference for the extension of the problem set.

The following article offers an analytical overview of the currently available software technologies designed to assist in creation, dissemination, and most importantly performance of interactive electroacoustic art. By grouping the software into two basic groups based on their interfaces, my aim is to provide a comprehensive list of two groups' strengths and shortcomings, therefore exposing common issues that arise whenever a composer utilises such software interfaces in performance settings. Finally, as an incentive in solving a number of given problems, the author will present RTMix, his own software creation that has been designed primarily as a standardised interface for the purpose of easier production, performance and dissemination of the interactive electroacoustic artwork.

This article discusses space and interactivity in relation to some of the author's compositions for performers and computer. It outlines approaches to musical space relevant to those works arising from the realms of acousmatic, instrumental/acoustic and soundscape composition, and explores the conflict arising when a variety of listening practices are employed by the spectator-listener. This conflict challenges the perceived boundaries that differentiate genres, and also challenges the significance of existing ‘instrumental’ definitions of interactive computer music to the author's work. The author's approach to investigating this issue through composition is discussed, using two pieces as examples: Words on the streets are these (2001), an interactive installation, and Still Life (2002), a concert piece for string quartet and live electroacoustics. Technical and aesthetic aspects are outlined, specifically in relation to the experience of the spectator-listener. The overall aim is to emphasise the importance of considering spatial issues in composing interactive music, and to examine how the interplay of spatial concepts might be explored in practice.

This article is intended to raise some points of interest and mark out some pointers for alternative approaches to the design and execution of interactive music systems and artworks which pursue interaction that:

[bull ] does not include any pre-defined pathways,

[bull ] takes dynamic morphology as its foundation, and

[bull ] implements dynamic software infrastructures, built on the object-oriented model, providing dynamic instrument instantiation, orchestration and timbral control.

It is intended that such design would be a precursor to a new approach to interactivity that responds more directly and uniquely to those who engage in the work, and in so doing rewards them more richly for their time, energy and enthusiasm.

In mixed electroacoustic music it is common to find the erroneous conception according to which interaction should base itself exclusively on the fusion between instrumental writing and electronic devices, whereas the contrast between these sound spheres is as significant as the fusional states. Although fusion may be seen as the most important ingredient for an efficacious compositional strategy concerning interaction, it is actually through contrast that the identities of spectral transfers in mixed composition can be evaluated by the listener. This text intends to introduce a discussion about the many possibilities offered by the morphology of interaction between acoustic sources and electroacoustic resources and structures. In this sense it tries to identify intermediate types between the extremes of pure fusion and pure contrast, which can be established by the composer that sees in interactive music one of the most advantageous poetic realms of electroacoustic music.

Spatial elements in acousmatic music are inherent to the art form, in composition and in the projection of the music to the listener. But is it possible for spatial elements to be as important carriers of musical structure as the other aspects of sound? For a parameter to serve the requirements of musical development, it is necessary for that parameter to cover a range of perceptually different states. For ‘space’ to be more than a setting within which the main active elements in the structure unfold, it needs to satisfy these requirements. This paper explains a number of important spatial composition strategies available to the acousmatic composer in light of current technology and sound reproduction situations. The analysis takes an aesthetical rather than a technical standpoint.

Modalys-ER is a graphical environment for creating physical model instruments and generating musical sounds with them. While Modalys-ER provides users with a relatively simple-to-use interface, it has only limited methods for mapping control data onto model parameters for performance. While these are sufficient for many interesting applications, they do not bridge the gap from high-level specifications such as MIDI files or Standard Western Notation (SWN) down to low-level parameters within the physical model. With this issue in mind, a part of Modalys-ER has now been ported to OpenMusic, providing a platform for developing more sophisticated automation and control systems that can be specified through OpenMusic's visual programming interface. An overview of the MfOM library is presented and illustrated with several musical examples using some early mapping designs. Also, some of the issues relating to building and controlling virtual instruments are discussed and future directions for research in this area are suggested. The first release is now available via the IRCAM Software Forum.

The Organised Sound Volume 7 CD contains both audio and video. Video material can only be viewed from a computer system. The CD will play all the audio tracks and sound examples in a standard audio CD player.