Impromptu: a piece with liberal character and improvisation, generally written for only one instrumentMonodrame: a drama which characters are introduced from only one point of viewImpromptu pour un monodrame expresses the idea of a bassoon perceived through a multiplicity of musical characters, each one marked by specific vocal colours and writing styles. Noticing the vocality constantly presents in the sound of the bassoon, I used formant filters, in the electronics, to accentuate and reproduce characteristics of the human voice, resulting in 5 "virtual" bassoons. The counterpoint between the real bassoon and the virtual bassoons, diffused through vocal filterings, strengthens and adds dimension to the concept of the musical characters in this drama within a rather free form. The piece consist of an introduction followed by three sections. Each section represents a confrontational situation between musical characters in new polyphonic relations.