Pièce en trio I is, like so many trios in organ literature, not easy to play, with the hands and feet moving independently of each other. Three chromatically related tonal centers are combined to create poly-modality. Theoretically, this would make for grinding dissonances, but the overall sound becomes quite consonant, due to the large distance between the voices and the ample acoustics of the church. Each voice has its own rhythm and tempo, giving an impression of loose construction. The timbre of the voices is very diverse; the bass has low-sounding 16', 8' and 6' principals (the latter emphasizing the third overtone, a perfect fifth). Conversely, the soprano has a very high sound produced by a 1' flute. The middle voice adds a third colour, of an 8' reed. The tonal centers are C, B and C-sharp for the bass, soprano and middle voice
