Assai lento - Allegro troppo br The first movement is in a modified version of traditional sonata form. There are clearly delineated sections – introduction, exposition, development, recapitulation and coda – but Bartók eschews the customary relationships between keys, beginning the movement in F sharp and ending in C major, with excursions into several unexpected keys in between. The rhythm of the movement is varied within an overall 98 time. The movement is also untypical of classical sonata form in that it constitutes half the playing time of the whole work. br Sonata for two pianos and percussion, first movement (excerpt) br This segment of Bartók's Sonata for two pianos and percussion features pedal glissandos during a timpani roll. br Problems playing this file? See media help. br Lento, ma non troppo br This movement displays the classical "middle movement" ternary a-b-a form. It is an example of Bartók's "night music" idiom. br Allegro non troppo br The third movement is a rondo-like dance, starting and finishing in C major. The pianos introduce the movement, followed by the xylophone. At the end of the work the last notes of the pianos die away, there is a concluding duet for snare drum and cymbal, and the sonata ends extremely quietly.