In scores which combine continuous prerecorded tape with live instruments, a click-track is often required to sustain the vertical cohesion between the two elements. This is usually an integral specification for the conductor, who will need to practise the pulse requirements with the tape before rehearsing as part of the score preparation. Beating time to a click-track which sustains the same pulse and time-signature throughout does not require comment. When tempi and irregular pulse are variable the conductor’s role becomes quite challenging and complex. Such a work is Tristan Murail’s Désintégrations (‘pour bande synthétisée et 17 instruments’). Because the complete work is based on crotchet units with occasional fractional additions, timesignatures are replaced by integers, not only for convenience but also to relate to the click-track graphics, which are placed between bars as dotted lines.

This is especially useful when a subdivision of the unit has to be beaten, as in the sixth bar of Example 35. During pause bars when the ensemble is silent, the click is not present. In these bars Murail provides three cue clicks before the next ensemble entry, which are included in the score as in the opening bar of Example 35. With earphones in place the conductor has to combine listening intensely to the click-track while focusing equally on the instrumental ensemble. ‘Open earphones’ of the ‘Walkman’ type are recommended by the composer. As the sounds on the tape are derived from instrument sources, there is a close integration of the live and prerecorded elements which must always be balanced by the conductor in association with the electronics performer. The composer states that ‘there is one origin for both tape and instruments, their relationship being one of complementarity. The title of the piece refers to how the tape element ‘diffracts or disintegrates their [the instruments’] timbre’. So there are three elements which the conductor has to relate to: the tape, the click-track and the live ensemble. The earphones are the most important part of the control required. An alternative to the kind of earphones the composer recommends are open headphones, often used in recording studios.