The history of music is a history of performers continuously transcending what were thought to be limits, and maybe the simple existence of such challenging scores as Le marteau sans maître and Zeitmasze was enough to encourage a new race of modern virtuosos, who detected in postwar music an invitation to extend the possibilities of performance. This was something new. Virtuosity in previous ages had been the domain of the composer-performer, and where performers and composers were tied in personal and professional relationships, as with Brahms and Mühlfeld or Stravinsky and Dushkin, the result was not a wild extrapolation of technique. But music now was in an extreme situation, and the new music of the 1960s, especially, was often a music of extreme and unprecedented demands. The rapid turnover in compositional technique was paralleled by rapid extensions of what could be expected from instruments and voices -- extensions which eventually took on a life of their own, as instrumentalists began to feel that composers were not necessary, that virtuosity had its best display as improvisation.
The revolution in performance practice, at its height in the mid- 1960s, had effects which defy easy summary. Woodwind players found it possible to produce 'multiphonics' (i.e. chords), either by using particular fingers or by singing into their instruments; they could also make percussive noises (by tapping on parts of the instrument), microtones, and unusual sounds created by means of more or less severe alterations to the embouchure and mouthpiece. Many of these devices were also found possible on brass instruments. On strings, new sounds could be obtained by unconventional bowing pressures, by bowing on unconventional parts of the instrument, by striking the instrument in various ways, and so on. Changes in piano technique have tended to be more straightforward tightenings of traditional demands in terms of dexterity, but percussionists have found vastly wider scope, in terms of their instrumentaria, their techniques, and their musical importance. It is enough to note that a virtuoso percussionist could hardly have existed in western music before the 1950s -- Stockhausen had to write Zyklus because no test pieces for the species existed -- whereas percussion ensembles and soloists are now a normal part of musical life.
The simplest possible response to these new riches is to use them as extensions of timbral resource, without letting them influence the premises of creative