Proceedings of the 15 th International Conference on Auditory Display, Copenhagen, Denmark May 18 - 22, 2009 A GRAPH-BASED SYSTEM FOR THE DYNAMIC GENERATION OF SOUNDSCAPES Andrea Valle, Vincenzo Lombardo, Mattia Schirosa CIRMA-Universit` a di Torino via Sant’Ottavio 20, 10124, Torino, Italy andrea.valle@unito.it, vincenzo@di.unito.it, mattiaschirosa@yahoo.it ABSTRACT This paper presents a graph-based system for the dynamic gen- eration of soundscapes and its implementation in an application that allows for an interactive, real-time exploration of the result- ing soundscapes. The application can be used alone, as a pure sonic exploration device, but it can also be integrated into a virtual reality engine. In this way, the soundcape can be acoustically in- tegrate in the exploration of an architectonic/urbanistic landscape. The paper is organized as follows: after taking into account the lit- erature relative to soundscape, a formal definition of the concept is given; then, a model is introduced; finally, a software application is described together with a case-study. 1. INTRODUCTION The term “soundscape” has been firstly introduced (or at least, the- oretically discussed) by R. Murray Schafer in his famous book The tuning of the world [1]. Murray Schafer has lead the research of the World Forum For Acoustic Ecology, a group of researchers and composers who empirically investigated for the first time the “environment of sounds” in different locations both in America and in Europe. Murray Schafer and his associates studied for the first time the relation between sounds, environments and cultures. Hence on, the diffusion of the term has continuously increased, and currently the concept of soundscape plays a pivotal role at the crossing of many sound-related fields, ranging from multimedia [2] to psychoacoustics [3], from job environment studies [4] to ur- ban planning [5], from game design [6] [7], to virtual reality [8], from data sonification [9] to ubiquitous computing [10] [11]: in particular it is a fundamental notion for acoustic design [12] [13], electroacoustic composition [14], auditory display studies ([15]). Indeed, it can be noted that such a diffusion of the term is di- rectly proportional to the fuzziness of its semantic spectrum. It is possible to individuate three main meanings of the term “sound- scape”, related to three different areas of research: • Ecology/anthropology [16]. Since Murray Schafer’s pio- neering work, this perspective aims at defining the rele- vance of sound for the different cultures and societies in relation to the specific environment they inhabit. A sound- scape is here investigated through an accurate social and an- thropological analysis. The goals are two. On the one side, the researchers are interested in documenting and archiving sound materials related to a specific socio-cultural and his- torical context. On the other side, they aim at leading the design of future projects related to the environmental sound dimension. • Music and sound design [17]. The musical domain is par- ticularly relevant. All along the 20th century, ethnomusi- cological studies, bruitism, “musique d’ameublement” and “musique anecdotique” have fed the reflection on environ- mental sound dimension as acoustic scenery or as scenic atmosphere [18]. At the same time, musique concr` ete has prompted composers to think about sounds as sound ob- jects. During the ’60-’70s many composers started working with sound field recording. Sharing the musique concr` ete attitude towards sound, they have been strongly influenced by the soundscape studies. Not by chance, many of Murray Schafer’s associates were composers. Thus, the concept is widely present in many contemporary musical forms, as the soundscape itself is regarded as a form of “natural” music composition (in general, cf. [19]). More, “soundscape com- position” identifies a mainly electro-acoustic genre, start- ing from natural acoustic environmental sounds, sometimes juxtaposed with musical scores. Also, sound designers work- ing for cinema and TV have contributed to the diffusion of the term, indicating with “soundscape” the idea of an acous- tic scenario to be added/adapted to the moving image ([20], cf. [21]). • Architecture/urban planning [22]. In recent years, electro- acoustic technology and architectural acoustics have allowed to think about the relation between sound and space in a new form, in order to make citizens aware of the sonic en- vironment (the soundscape) they live in, so that they can ac- tively contribute to its re-design. Many architectural projects have been developed descending from these assumptions [23]. The concept of “lutherie urbaine” has been proposed as a combined design –of architecture and of materials– for the production of monumental components located in pub- lic spaces and capable of acting like resonators for the sur- rounding sound environment [24]. It must be noted that such a complex and rich set of features re- lated to soundscape is extremely relevant because it demonstrates that the problem of the relation between sound and space cannot be solved only in acoustic or psycho-acoustic terms. An acoustic or psycho-acoustic approach considers the relation among sound, space and listener in terms of signal transfer [25]. Acoustic ecol- ogy, through a large body of studies dedicated to soundscape de- scription and analysis ([1], has pointed out that the perception of soundscape implies the integration of low-level psychoacous- tic cues with higher level perceptual cues from the environment, its cultural and anthropological rooting, its deep relations with hu- man practices. The integration of soundscape in a landscape doc- umentation/simulation is crucial in order to ensure a believable experience in human-computer interaction [26]. A consequence of the integration among different perceptual domains and among multilevel information is that the study of soundscape requires to include phenomenological and semiotic elements. In this sense, the study of soundscape can benefit from the research in “audio- vision”, i.e. the study of the relation between audio and video in audiovisual texts (film, video etc) [27]. More, soundscape stud- ies have highlighted the relevance of different listening strategies in the perception of the sonic environments: from a phenomeno- logical perspective ([28], [29]) it is possible to identify an “index- ICAD09-1