Convolving a clarinet with a piano

In 1985 the composer Pierre Boulez wrote "Dialogue de l'ombre double" for live and pre-recorded clarinet, whose musical score includes technical instructions for use during the recording session and the live performance. The composer's recording instructions define studio acoustic conditions like: the use of three microphones (direct, indirect and by piano), the distance between the first two microphones and the clarinet, the amount of reverberation and the procedure for exciting a piano by the clarinet sound. This paper reports about a different way of playing this composition that while fulfilling the composer's prescriptions, acoustically enhances the musical performance. In our acoustical interpretation in fact the recording of the clarinet "double" was performed into an anechoic room and the use of convolution techniques was adopted for the fulfilment of the score prescriptions. The first live performance based on this "acoustically enhanced" method has been given in Rome the 1st February 2005 with a great success. The procedure for obtaining the impulse responses for indirect and reverberation sound as well as for the effect of mixing resonating strings sound of the piano with the clarinet one are here focused in some detail. Audio processing examples and significant excerpts from the performance are also briefly reported.