New directions and non-linear musics
It goes without saying that an interactive or adaptive music is necessarily nonlinear. Musical nonlinearity has been a pre-occupation of composers and music practitioners since long before the technology that might make it a reality existed, or rather, a technology that could, at least, spontaneously account for the decisions and movement (in a physical space) of its listener and create a desired musical experience – still determined – but in an indeterminate environment. In a sense, Messiaen’s much celebrated “end of time,” in which forms “appropriate to a non-linear, non-directed music” which express “new kinds of ‘timeless’ time” (Cross 1998: 61) need not simply be regarded as a concert hall irrelevance in our discussion of dynamic music for a new media today. Indeed, the exploration of this musical stasis, in direct contrast to a properly linear tonal music rooted in the exploration of (and eventual return from) familiar harmonic territories, has been an almost singularly determining factor characterizing art music of the twentieth century (and beyond). As Jonathan Kramer poetically puts it, the epoch of Stravinsky and Debussy is regarded no longer by
the tension-laden pedal points of Bach but rather segments of musical time that are stationary and have no implication to move ahead; no longer textural constancy as an overlay to harmonic motion but now the freezing of several parameters into miniature eternities. (Kramer 1988: 44)
Kramer has further suggested that a sense of immersion, a still ambiguous term, is achieved in music by minimizing “the distinction between the self and the other” (Kramer 1988: 44), and that this was, in part, made possible precisely by the progressive erosion of linearity in contemporary music (the process detailed in the quote above). In particular, he cites the example of experimental composers in the 1960s who sought not only to diminish the distinction between composers, performers, and listeners, but between the work and the environment in which it is experienced as well (Kramer 1988: 382). Incidentally, his suggestion that dream states, drug use, and certain mental illnesses were formative to such artistic experiments – in so far as suspension of temporality was an aesthetically desirable outcome - resonates acutely with the oneiric nature of TMD’s narrative. The fact that the drama/narrative invokes in the player a state of reminiscence, social uncertainty, and mistrust - and indeed outright hallucination (reliving the memories of a friend) - already somewhat confirms the pliability that the new music idiom, with its requisite vocabularies of immersion and engagement, has with the nature of the narrative in question here. Technology, too, as well as the innovations it has engendered, has been inextricably linked to this reimagining of “time” in modern music. Be it Debussy’s music for the “century of airplanes,” or the enthusiastic appropriation of electronic instruments by modernist composers such as Varèse for (as in just one example) the spatial distribution of sound in specially constructed multimedia performance spaces. Not to mention the contemporary experiments in human-instrument interaction carried out at, among other places, IRCAM. It is an aim of this article to make the case, in part and not otherwise put forward, that such music traditions ought to have a great deal to contribute to any emerging narrative-based mediums that, like TMD, seek to explore the extent to which a player might be immersed. Indeed, this assumption will come to frame, in part, the discussion that is to come of the music itself.
A contemporary development among practitioners of avant-garde and electroacoustic music that is particularly relevant for the discussion to follow is that of soundwalking and the accompanying, though broader, conception of an “acoustic ecology.” Coined by R. Murray Schafer and associated with composers such as Hildegard Westerkamp, a soundwalk is any excursion whose main purpose involves “listening to the environment […] It is exposing our ears to every sound around us no matter where we are” (Schafer 1978: 71). Such a development can be seen to arise out of a tradition which had - simultaneously and perhaps contradictorily - sought to incorporate the extra-musical into an all-embracing compositional practice (say, Varèse) and to problematize the hierarchical modes of mediation associated with established musical practices (typically associated with the concert hall). This could be referring to the Cagean dictum of liberating sound and “erasing the ego of the artist”: relegating much of the actual material and sound-production to improvising musicians, chance procedures, and natural/pre-existent soundscapes (LaBelle 2006: 20). Soundwalking, a capacious term indeed, might simply involve a prearranged (or composed) walking route that factors in the sounds of the environment. It may also be a composition designed to accompany a walk (which may or may not incorporate natural sounds) or a piece of music (electroacoustic or otherwise) that is designed to evoke the peripatetic or ambulatory experience. Such compositions are properly non-linear, often indeterminate, and already repurpose the agency of the listener, not as a passive agent in the listening experience but as an active participant in the creation and unfolding of the composition. Of soundwalking’s radical capacity, John Levack Drever says the following:
The concatenation of locomotion with a state of readiness for attentive unprejudiced listening that protracts beyond the walls of the consecrated sites of dedicated otic practices (that is, concert hall, church, lecture theatre) form the commonality that is soundwalking. (Drever 2009: 163)
Out of this, it is worth drawing particular attention to the concept of acoustic ecology, a way of conceiving sound in terms of a self-sustaining and reciprocal environment. As Schafer puts it, the term “acoustic ecology” suggests that we attempt to hear the acoustic environment around us as a “musical composition and further, that we own responsibility for its composition” (Schafer 1977: 205). It seeks, then, to reimagine space in terms of what we hear rather than what we see (Schafer describes this as the “eye culture”). Enduring and far-reaching in its influence, it gave rise to the idea of a soundscape in which the sounds that we hear in our everyday life are not simply discarded as noise. Instead, such sounds are understood to contain an innate kind of musicality. That this should have some special importance now will become apparent later in the article.
The debates pertaining to non-linearity are not unique to music. A great many of the ideas upon which we have drawn have their analogue in the discussion of (among other things) modernist literature. Espen J. Aarseth, in his discussion of hypertext fiction, has developed the concept of an ergodic literature in which “nontrivial effort is required to allow the reader to traverse the text” (Aarseth 1997: 1). In addition to the textual organization unique to hypertext fiction in particular, an ergodic literature assumes a centering of attention onto the user (of the text) as a “more integrated figure” than might be the case in more typically linear narrative-based mediums. The term ergodic has since found common use in the academic discussion of video games and might prove to be useful here. However, that a text might, as Aarseth seems to suggest, require only trivial forms of engagement, strikes me as a rather troubling assumption. Indeed, any medium - be it of the overtly narrative sort (literature) or the more abstract (say, music) - has its immersive potential conditioned by a complex hermeneutic response unique to, and contingent upon, the faculties and priorities (creative or otherwise) of the individual or communities experiencing it. That this might be the case of traditionally linear mediums is evidenced in the first part of this section. Aarseth elsewhere conceded the dangers of an overinvestment in terms like non-linearity, though: “the linear can flirt with nonlinearity, but the nonlinear cannot lie and pretend to be linear” (Aarseth 2003: 764), and therein lies a curious paradox. A Choose Your Own Adventure book could have the reader flicking back and forth between pages, giving only the most superficial and illusory of choice to its reader, but is this necessarily a richer text than say, Joyce’s Finnegan’s Wake? Joyce’s late masterpiece contains an incoherent overabundance of linearly presented meanings, associations, etc.; the resultant work invites a multiplicity of interpretative responses and rereads.
Non-linearity is by no means a clearly defined or definable term, as I hope to have established above. Moreover, the relationship between non-linearity and the here central principles of “interactivity,” “immersion,” and even “presence” are significant, if difficult to establish; indeed, I have been mostly quite imprecise in my adoption of them so far. This is, however, evidence of a great deal of uncertainty across a range of disciplines which draw freely and creatively from them and offer contrasting, often contradictory, accounts as to what they actually mean, not least in the work on new narrative-based media such as TMD itself. Though I have no intention of giving any concrete assertions on the nature or meaning of these words here, I would like to add some cautionary insights. All classical and modern arts are, in the words of media theorist Lev Manovich, “interactive” by nature. He cites, as examples, “ellipses in literary narration, missing details of objects in visual art, and other representational ‘shortcuts’ which require the user to fill in missing information” (Manovich 2001: 56). Indeed, he goes on to propose a “myth of interactivity,” which assumes of new media, too soon, its capacity to transfer authorship to its user through seemingly superficial processes of interaction. Such myths risk equating “interaction” with the physical act of human-object interface at the expense of psychological interaction.
The psychological processes of filling-in, hypothesis formation, recall, and identification, which are required for us to comprehend any text or image at all, are mistakenly identified with an objectively existing structure of interactive links. (Manovich 2001: 57)
By confusing the internal freedoms involved in the mental reconstruction of the artwork with an externalized, and typically digital, ideal of (an always contingent) choice-making - Manovich offers up Althusser’s concept of “interpellation” - we are asked, in effect, “to mistake the structure of somebody’s else [sic] mind for our own” (Manovich 2001: 61). Of video games, a contrasting, but critically complementary, “immersive fallacy” has been observed. The immersive fallacy contains the widely held but largely unexamined assumption that the “pleasure of a media experience lies in its ability to sensually transport the participant into an illusory, simulated reality” (Salen and Zimmerman 2004: 451),typically, to such an extent that any framing device (say the boundaries on a television) melt away. That this is an incomplete understanding of immersion should seem obvious, and in the context of computer games at least, it is the processes involved in “play” itself that are overlooked. For Katie Salen and Eric Zimmerman, “play is a process of meta-communication, a double-consciousness in which the player is well aware of the artificiality of the play situation." Engagement through play is a far more complex proposition, and the potential it offers this debate may ultimately be more enriching. Tetris is an example of a game (and a particularly enduring one at that) in which immersion is not bound to a “sensory replication of reality” (Salen and Zimmerman 2004: 452). Immersion then should not simply be predicated on a basic suspension of disbelief, and this strikes me as particularly important when trying to carve a place, in projects like TMD, for music. After all, if the goal is the reproduction of some form of immersive reality (or rather, a mixed-reality) – and in so doing the production of a diegetic world unhindered by the non-diegetic – should the musical score, rich in otherworldly associations, be cast aside? Given the abstractions that music typically offers (it is the abstract art par excellence), a broader understanding of the limits of interactivity and immersion ought to be developed, if indeed music is to be a fully contributing and creative force for the future of transmedia and pervasive drama efforts. In the meantime, we should seek to resist casting music as simply the icing on the cake (or at worst, a glorified elevator Muzak!). I hope to reinforce Frances Dyson’s contention, to consider sound or music not “as the precondition for virtuality or cyber space, but to show the way that sound, technology, and culture have combined to create a rhetorical structure through which prior notions of embodiment, materiality, humanity, art, and science are reassembled for deployment in the information age” (Dyson 2009: 7).
 Hughes Vinet (Vinet 1999) has given some sense of IRCAM’s priorities. As well as the aforementioned human-instrument interaction, research interests include acoustics, music perception and cognition, synthesis, and computer-aided composition. All of these (as will become clear) bear some relationship to, and could contribute significantly towards, the types of work discussed here.
 It is worth noting that a discussion of music is largely absent from the literature about pervasive storytelling. This is likely the case because it is a relatively new medium and theorizers of sound have simply not come around to discussing it yet. Given the capricious and site-specific nature of the format, there has also been little opportunity to preserve what music might have been written. Practice-orientated textbooks intended to provide a survey of past productions and advise on future design of “pervasive games” have little (if any) mention of music or sound (see Montola, Stenros and Waern 2009).
 There have been a number of attempts at clarifying the meanings of the terms “immersion” and “presence” within which, it has been noted, there have been inconsistencies (see Slater 2003).