In "Grove", Nichols divides the chamber works into three clearly differentiated periods. The first four sonatas come from the early group, all written before Poulenc was twenty-two. They are for two clarinets (1918), piano duo (1918), clarinet and bassoon (1922) and horn, trumpet and trombone (1922). They are early examples of Poulenc's many and varied influences, with echoes of rococo "divertissements" alongside unconventional harmonies, some influenced by jazz. All four are characterised by their brevity – less than ten minutes each – their mischievousness and their wit, which Nichols describes as acid. Other chamber works from this period are the "Rapsodie nègre", FP 3, from 1917 (mainly instrumental, with brief vocal episodes) and the Trio for oboe, bassoon and piano (1926).