Prepared and Unprepared Techniques of Improvisation in Foreign Jazz Instrumental Music of the Second Half of the XX Century

The purpose of the work is to analyse the prepared and unprepared techniques of improvisation in foreign jazz instrumental music of the second half of the XX century, as well as to determine the trends and features of their development. The research methodology involves the use of historical, analytical, and comparative methods, which allows revealing the peculiarities of the development of creative techniques in jazz instrumental music of the stated period. The scientific novelty of the work lies in the fact that prepared and unprepared improvisation techniques in foreign jazz instrumental music of the second half of the XX century are investigated for the first time, the analysis of which makes it possible to find out how these techniques and jazz instrumental music of the specified period developed as a whole. Conclusions. In the second half of the ХХ century, prepared and unprepared improvisations developed dynamically. Prepared improvisation is a fairly common creative technique in jazz music, which has its roots in academic music. The main principle of prepared improvisation is that it is planned in advance by the performer. It becomes widespread in jazz in the first half of the ХХ century during the swing era, during the heyday of big jazz orchestras and big bands. In the second half of the ХХ century the prepared improvisation technique develops freely, interacts with other improvisation techniques (collective, solo, choral, and modal). However, at the same time, jazz music has been associated precisely with unprepared improvisation since its inception. This technique does not require prior preparation, the birth of music occurs directly at the moment of making music. If prepared improvisation can be positioned as a phenomenon of limited improvisation, then unprepared improvisation gives complete creative freedom to the musician. In addition, it should be noted that the principles of unprepared improvisation are quite close, similar and related to the techniques of free and spontaneous improvisation. To a large extent, these techniques are used in avant-garde trends and free jazz. In the development of unprepared improvisation in jazz instrumental music of the second half of the ХХ century it is difficult to single out specific periods that are marked by certain characteristic and innovative tendencies of formation. 
Key words: prepared improvisation, unprepared improvisation, creative and performance techniques, jazz instrumental music.