Page  00000001 A STETHOSCOPE FOR IMAGINARY SOUND INTERACTIVE SOUND IN A HEALTH CARE ENVIRONMENT Pedro Rebelo, Michael Alcorn, Paul Wilson Sonic Arts Research Centre Queen's University Belfast ABSTRACT We discuss design strategies and system development in relation to an interactive sound installation created for the Royal Victoria Hospital in Belfast'. In contrast to other initiatives involving music in health care environments, the impetus of this project does not reflect therapeutic concerns, but rather the intent of enriching hospital users' experience through the arts. This paper examines challenges brought up by this work in technical, design and social contexts. 1. INTRODUCTION The space in which sound is heard contributes not only to the way we perceive it acoustically, but also infuses sound with particular meaning and context. Public spaces such as museums, town squares or hospitals suggest specific types of behaviour and engagement. In recent years we have seen an increase in initiatives leading to sound installations for sites of a public nature. The design of such works poses challenges which differ from those of composition for a traditional concert environment. In addition to musical structures and sound materials, the designer of sound for public spaces needs to engage with architectural, social and environmental aspects of a particular site. This project is part of a national initiative to bring artwork into healthcare environments. "The Arts and Environment Project seeks to improve the quality of the physical healthcare environment throughout The Royal Hospitals and to enrich the experience of hospital users through the arts." ( [1] 2. FROM OUTSIDE TO INSIDE In considering the history of sound and listening in a clinical environment we can engage with particular layers of meaning and function. The internal sound of the body has historically constituted one of the most practiced modes of diagnosis. The role of sound in a clinical context is discussed by Jonathan Sterne [2]. Sterne draws a history of auscultation in relation to the stethoscope as a technology 1 This project is funded by the Arts Council of Northern Ireland through the National Lottery. for framed hearing. The relationship between the physician's practice and technologies such as the stethoscope turned members of the medical profession into what Stern refers to as "virtuoso listeners". In the late 19th century, the shift from a listening situation based on doctorpatient spoken exchanges to one of detached framed listening led to significant change in clinical practice. Whereas doctor-patient dialogue was inevitably modulated by the patient's own response to symptoms, an outside listening of the involuntary body sonic makeup was seen as a move towards clarity, objectivity and rationalisation. This particular listening culture poses interesting questions when considering a reversal. This installation proposes a mediated listening environment which reflects not only the outside of the body but also imaginary environments. Sonic relocations of external environments and their soundscapes turn this sound installation system into a stethoscope for imaginary sound. 3. THE SITE The Royal Victoria Hospital in Belfast is part of Northern Ireland's largest and best-known hospital complex. The site for this project consists of a main circulation corridor in a recently constructed section of the hospital. The corridor acts as a main route for staff, visitors and patients. The hospital estimates that around 1,000,000 people per year walk through this corridor. The space (fig 2) provides access to clinics, wards and a cafeteria, as well as connecting to other levels in the building via lifts and escalators. The architecture (Capita Percy Thomas) reflects a desire to bring the outside world into the space by providing large areas of natural light and features such as interior gardens and water fountains. The architecture of the corridor suggested a number of possible spatialised sound strategies. In order to take advantage of both the distinct character of each corridor section and its scale as a continuous space we have opted for a 16 channel sound system. The configuration below (fig 1) provides opportunities for both differentiation between sections and a certain degree of homogeneity throughout the corridor. In particularly the system can act as 16 discrete channels or as a single, holistic tunnel of sound.

Page  00000002 K> 14............. 1, Figure 1: Corridor Plan and Loudspeaker Layout 5. DURATION & MODULARITY The system has been implemented in Max/MSP/Jitter running on two Macintosh G5 computers connected via Ethernet. The permanent character of the work and associated need for robustness presented a major consideration in the design of the system. In order to implement a system which could reflect the idea of sound world fragments and at the same time allow for regular changes and adjustments we have developed a modular software environment. Once each sound world is implemented as a Max/MSP patch with associated sound files, it works as an isolated patch with individual interaction and spatialisation strategies. A daily cycle has been divided into periods of particular levels of activity (staff rounds, visit times, meals, quiet times when only staff and patients are circulating in the corridors). According to the time of the day a specific number of patches are candidates to be loaded into the system. The management of the daily cycle has been implemented as an Applescript application which is responsible for starting up and shutting down the computer, choosing which group of patches are candidates to be loaded depending on the time of day, opening patches and quitting Max/MSP depending on each predefined or randomly selected duration for a given patch. A duration for each patch is written into a text file every time a Max/MSP patch loads. The Applescript application reads this text file and uses the duration as a delay before quitting Max/MSP and loading another patch from the set corresponding to the time of day. By writing a text file with a duration which is common to both the Applescript and the Max/MSP patches the system automatically performs volume fades at the start and the end of each segment. 6. VIDEO TRACKING The choice for video tracking as a way of sensing the environment was made in response to the need for a relatively transparent interface. The social environment suggested by the hospital's corridor is characterised by somewhat unpredictable levels of engagement. Whereas Figure 2: Site 4. SOUND WORLDS The installation comprises a large number of selfcontained sound worlds. These range from environmental phonographies to instrumental and vocal materials. Each of these sound worlds acts as a suggestive 'window'. A design criteria established together with the client, specified a somewhat fragmentary approach to the installation. One hears short segments out of semigenerative environments which could notionally sound for hours. The non-linear character of each environment allowed for the use of randomised durations (between two and three minutes) for both sounding and silent segments, adding variety and unpredictability to the work. This has the effect of presenting a dynamic environment in which the silent transitions between sound worlds are as important as the sound worlds themselves.

Page  00000003 it is a possibility that a visitor stops and engages with the sound world and its interactive elements, it is likely that for most of the time listeners are unaware of their interaction. This aspect of the space provides an opportunity for sensing levels of activity and movement which are in essence involuntary, not unlike the stethoscope's sensing the unintentional sound world of the human body. Four video cameras are positioned throughout the corridor in locations that are relative to particular sets of speakers so as to define four speaker/camera interactive sets. The analogue video signal is composited into a quad configuration for tracking and analysis undertaken in Jitter. We have chosen to use Timothy Place's tap.jit.motion object in order to describe the video in terms of general levels of activity rather than the tracking of individuals, This object compares a frame with the previous frame and reports back the difference and the weighted location of the difference. One instance of the object is used for each camera. Q 4 Video Cameras Quad | AD Video Processor I I Processor Firewire G5: Video Audio S5GS: Audio Interface 16 Loudspeakers MOTU24io Figure 3: System Architecture 7. INTERACTION STRATEGIES As mentioned above, the nature of participation on the part of the listener has suggested its own modes for interaction. The possibility for moving from the reactive to the interactive is presented in sound worlds in which specific actions such as crossing a virtual threshold cause a particular sound event which in turn may invite the listener to participate in a conscious way. Chadabe refers to two approaches to the issue of mapping "controller" gestures to algorithmic parameters; the hierarchical and the network [3]. These two approaches are equated with 1. deterministic instruments in which a performer is in full control of a system's output, and 2. indeterministic ones which places the performer in varying degrees of influence within a complex system. The latter is based on the notion that in a network structure each node has the potential to influence the system in a non-linear or unpredictable way. Chadabe is primarily concerned with interactive instruments in a context of performance. An installation environment poses rather different questions, especially when the context for participation is not clearly defined. Whereas a sound installation in a gallery presents a clear invitation for engagement, the hospital environment is largely characterised by involuntary participation. Interactive strategies used in the installation can be categorised as either environmental or instrumental. 8. ENVIRONMENTAL STRATEGIES An environmental approach to interaction models a sound world according to degrees of variability. Input sensed from the participant's actions, in this case video motion data, is not mapped to sound events designed as a cause of such action. It is rather treated as environmental change which influence the way a sound world generates itself. This approach bears similarities with Chabade's network method. Examples of such strategies include: 1. accumulation of data over a period of time to reflect changes in a time scale that is longer than that of individual sound events, 2. the modulation of generative events with a view to the introduction of variability on otherwise predictable or linear sound worlds. The use of the video-motion data has in some instances also been used as arbitrary audio signals written into a buffer and subsequently used for filtering and convolution. Although reflecting levels of activity in the irregularity of the signal this approach does not directly map movement into sound. Here, the concern is not for a representation/translation of spatial activity into sound but rather the generation of sound signals from the motion data itself. 9. INSTRUMENTAL STRATEGIES Instrumental approaches to video-based interaction are inevitably made problematic by the lack of physical resistance. Whereas musical instruments can be characterised as a set of contingencies which offer varying degrees of resistance to human actions [4], a video-tracked space is intrinsically linked to the dynamics of architecture and circulation. Whereas a lack of physical resistance and associated need for effort might be an important aspect of performance, in this context, a video interfaced instrument is characterised by the involuntary movement of the participants; not unlike the design of wind chimes which simply assumes a certain level of activity and no expert interaction. Examples of such strategies include the implementation of invisible thresholds which act as triggers and modulation objects for discrete sound events. This type of strategy is often combined with playback of precomposed soundscapes so that the instrumental trigger

Page  00000004 relates to one and not all elements of the sound world. An example of this type of strategy is a patch which juxtaposes the triggering and modulation of recordings of cockerel calls on a layer of pre-recorded environmental soundscapes. In this instance, movement in the corridor is analysed through a matrix which on one axis triggers pre-recorded samples and on the other introduces modulation degrees (micro variations in playback speed) to those samples. Conclusion We have addressed design issues in relation to an interactive sound installation for a hospital environment. The emergence of design strategies resulted in the interaction between three main forces; 1. the site, 2. the relationship with the client, 3. each composer's response to the cultural and social environment of the hospital. We found the process of designing a system which would respond to the requirements of robustness and modularity to be a central element of this project. The semipermanent nature of the installation suggested the need for updates and revisions which will be informed in part by a number of recorded interviews with staff and visitors at the hospital. Future work includes the analysis of responses from these interviews as well as of video documentation of the installation at work. We hope to gain some insights into how visitors respond to the work and its interventional rather than therapeutic nature. References [1] Royal Hospitals Homepage [03/05] [2] Jonathan Sterne (2003) Medicine's Acoustic Culture. In Bull, M. and Back, L. eds "The Auditory Culture Reader". Berg. Oxford [3] Chadabe, J. (2002) The Limitations of Mapping as a Structural Descriptive in Electronic Instruments, International Conference on New Interfaces for Musical Expression [4] Rebelo, P. (2004). Haptic Sensation and Instrumental Transgression. Senses Conference, London College of Music and Media, London