Multímetro

This section uses the Communication Constraints proposed by Clark and Brennan (1991) to understand how technological mediation can influence musical interaction. These constraints were previously used to consider forms of mediated human-human communication. In CDMI, technological mediation imposes constraints on the ways in which musicians can work together. Although this thesis does not attempt to make strict distinctions between different types of musi- cal activities, the influence of these constraints are important to acknowledge. Clark and Brennan (1991) defined eight constraints which can be used to compare communication modalities. These constraints, discussed in the following sub-sections, refer to the properties of the situation or con- text itself (i.e. co-located interaction), rather than the constraints imposed by an instrument or interface, or creative constraints a musician may adhere to as part of their artistic practice (Candy, 2007, Michael Gurevich and Marquez-Borbon, 2010). This discussion serves to highlight the role technology places in shaping, supporting and prohibiting certain forms of coordination and com- munication between groups of people whilst engaging in music-making. The discussion also stresses a number of distinctions between CDMI and other forms of group collaboration, and between CDMI and face to face verbal conversation.

3.3.1 Copresence

Clark and Brennan (1991) uses the term copresence to refers to situations where people occupy the same physical space and are therefore able to interact face-to-face. Within this thesis copres- ence has previously been discussed in relation to the ethnographic studies of groupwork (Furniss and Blandford, 2006, Heath et al., 1995, 2002b, Hutchins, 1996), and observational studies of conventional musical interaction (Gratier, 2008, Healey et al., 2005, Nabavian, 2009, Nabavian and Bryan-Kinns, 2006, Sawyer, 2003). Copresence is a natural context for verbal communi- cation, and copresence also affords non-verbal communication in the form of gestures, gaze, pointing, and orientation. Early research within CSCW attempted to recreate the experience of co-located interaction between geographically separated individuals using live video links (Ishii et al., 1993, Olson et al., 1995). However, it was soon realised that even with multiple channels of video, such systems provide a limited approximation of some aspects of co-located interac- tion (Hollan and Stornetta, 1992). For instance, gaze, eye contact and the ability to establishing reference to artefacts through pointing, are all potentially compromised by video mediated com-

munication. Groupware systems also attempt to recreate certain aspects of co-located interaction. The Workspace Awareness framework (Gutwin and Greenberg, 2002) used throughout this thesis is based on observations of co-located interaction, and contributes to an understanding of how awareness features can be mediated by technology to support remote collaboration.

Before the advent of technologies such as the internet, musical interactions between people would have relied more heavily on copresence. However, digital technology allows for a variety of remote interactions, such as file sharing, audio streaming, digital video-mediation and online composition systems. In attempting to classify systems to support musical interaction between people, Barbosa (2003) referred to copresence using the terms local and remote. This thesis focuses on co-located (local) musical interaction between people, mediated via a shared software interface. From a design perspective, this approach alleviates the need for an interface to support communication and interaction which is naturally afforded by co-location, although compared to acoustic instrument playing, the use of screen-based interfaces for musical interaction may affect the degree to which users communication their activities as a consequence of their physical movements.

3.3.2 Visibility

The constraint of visibility refers to the ability for people to see each other whist interacting. Face-to-face interaction would normally presuppose visibility, and remote video mediated com- munication also supports visibility, despite the participants not being co-located. Visibility might normally be the case for co-located musical interaction between small groups of musicians (Fen- cott and Bryan-Kinns, 2010, Gratier, 2008, Healey et al., 2005, Nabavian, 2009, Nabavian and Bryan-Kinns, 2006), although it has been noted that visibility is not necessarily essential for grounding in musical improvisation (Gratier, 2008). Visibility may not be assured in larger en- sembles of co-located musicians, such as orchestras, where musicians are spread out over a large area.

3.3.3 Audibility

The audibility communication constraint refers to the ability for people to hear each other during communication. This is assumed in verbal face-to-face communication, and is essential for tele- phone conversation, but is not necessarily a feature of other forms of mediated communication, for instance e-mail, video-only communication, or text-messaging. The sonic nature of music

presupposes the need for audibility for collaborative musical interaction, and the ability to hear others is one of the main ways in which musicians co-ordinate their actions. This thesis explores a number of aspects of the Audibility constraint, particularly in relation to the ways in which interfaces for collaboration can be designed to disrupt the congruence of audio presentation be- tween collaborators.

3.3.4 Cotemporality

The cotemporality constraint refers to receiving a contribution at the same moment that it is being produced by someone else. For instance face-to-face or telephone conversations can be regarded as cotemporal. However in contrast, communication formats such as e-mail can disrupt cotemporality by allowing messages to arrive out of sequence. Most real-time musical interaction relies on contemporality, not only for successful interaction between musicians, but also for the creation of music which is aesthetically pleasing (i.e., in time and in tune). Reflecting this, a fundamental concern for distributed technologies is network latency, which can heavily disrupt the cotemporality of musical interaction (Barbosa, 2003). Within the research presented in this thesis, contemporality is assured by several means. Firstly, colocating the participants allows face-to-face speech, secondly, the software environment was deployed on a high-speed local network (to minimise network latency), and the software (see Section 4.2) used a centralised mechanism to ensure that all musical events were delivered cotemporarily to all participants.

3.3.5 Simultaneity

Simultaneity refers to people being able to send and receive at once. In face-to-face and telephone conversation, interlocutors are able to speak at the same time. Simultaneity would usually be as- sumed where participants each have individual instruments or mechanisms for producing sound, and indeed it has been stressed that in activities such as group improvisation, musicians gen- erally contribute simultaneously, rather than taking turns (Sawyer, 2003), although some group members may be taking a more prominent role such as a lead player. The issue of simutaneity becomes blurred when considering multi-user instruments which require two or more people to jointlycontrol or co-author the sonic output of an instrument. Examples include the Tooka (Fels and Vogt, 2002), and experimental compositions such as Stockhausen’s Mikrophonie composi- tion (Maconie, 1989). In examples such as these, whilst the musicians are interacting in simul- taneity their actions are causing the interface/instrument to produce a single musical outcome,

rather than two distinct and simultaneous musical voices.

3.3.6 Sequentiality

Forms of communication such as e-mail allow contributions to go out of sequence, possibly lead- ing to confusion or misunderstandings. However, as with face-to-face conversation, contributions in real-time musical interaction cannot fall out of sequence. In real-time musical interaction, se- quentiality is also assured. Remote interaction and asynchronous collaborative activities may alter the sequence of musical contributions, however these activities are not addressed within this thesis.

3.3.7 Reviewability

Communication media such as letters and e-mail allow their contents to be reviewed after trans- mission, while speech is evanescent (Clark and Brennan, 1991) and fades away as soon as it has been uttered. Similarly, real-time musical interaction with conventional acoustic instruments does not include reviewability, as the sounds of acoustic instruments are ephemeral, and pass by in the same way as vocal utterances. Recording technologies allow speech and music to be reviewed after the event, although this arguably challenges their status as real-time activities.

Other forms of musical interactions may allow for reviewability, for example non-realtime composition systems may enable musicians to revise their contributions after they have been submitted. Real-time musical interaction which is based on the editing of repetitive looping phrases, such as in the Daisyphone (Bryan-Kinns, 2004), may also support reviewability in the sense that a musical phrase can be altered after it has been entered into the system. Similarly, (Gratier, 2008) stated that musical repetition is another essential part of musical grounding for improvising musicians.

3.3.8 Revisability

Forms of communication such as e-mail and letters allow messages to be revised before being transmitted. In some forms of musical interaction musicians may also be able to revise their contributions before they are shared with others. For example people composing music over a long period of time may work on ideas in private before bringing them together and sharing or combining them with the contributions of other people. Similarly, in real-time interaction, people may temporarily break away from the group or play ideas more quietly in order to revise and

formulate a contribution in private (Healey et al., 2005, Nabavian, 2009). This idea has previously been discussed with reference to the notion of mixed focus collaboration. Previous work on cotemporal and co-located musical interaction demonstrates that the inclusion of revisability, when presented in the form of private workspaces was favoured by collaborators during a group composition activity (Fencott and Bryan-Kinns, 2010).

3.3.9 Summary

This discussion of the communicative constraints imposed by technological mediation in musical interaction has performed several functions. Firstly, it has highlighted a number of ways in which music differs from other forms of communication. This is an essential distinction to make, as it has implications not only for understanding the ways in which people perceive sound, but also for understanding how interfaces must be designed so as to support musical collaboration. Crucially, group musical interaction in real-time relies upon audibility and sequentiality, and although some coordination mechanisms may rely on visibility, this may not always be available. Secondly, this discussion identifies a number of dimensions along which technological support for musical interaction can influence the kinds of activities a system is likely to support. A breakdown in simultaneity will be a serious issue for real-time interaction (a known and well attended problem for online collaboration), whilst constraints such as revisability are open for support in software interfaces. Finally, these two considerations serve to delimit the domain of study addressed in the remainder of this thesis, which, as outlined previously is real-time co-located interaction between musicians, supported through a shared software interface.