The synthesis model for the production of the source material of Lasciar Vibrare consists of a digital simulation of 4 impulse generators and 4 filter banks, each containing 31 parallel band-pass filters. The resulting sounds vary from percussive noises to sustained chords, depending on the bandwidth setting of the filters. The impulse generators are programmed in such a way that the amount of random deviation from a regular clock can be adjusted in very small amounts. When this deviation is ‘0’, the four generators are absolutely regular and in phase. By introducing some deviation they not only become less regular, but also less equal to each other. Here, a rhythmical aspect also gets a spatial implication; when the 4 impulses are reproduced through 4 loudspeakers around the audience, the localisation of a group of impulses is determined by the impulse that comes first. By increasing the deviation one arrives at a totally random distribution of impulses on the loudspeakers, which in the case of high pulse densities leads to all kinds of interesting spatial phenomena as well.
Subsequently this source material for the composition is systematically exposed to a number of sound transformations. In this way, a network of relations emerges, which is visualised in the form of a tree structure. The tree structure forms the basis for the way these materials are placed in a time structure. Different routes through the tree structure may lead to form variants.
The large form of Lasciar Vibrare v.4 contains a number of parts, the most of which are again divided into sub-parts. Part 1 has 4 sub-parts, part 2 has 3 sub-parts, part 3 has 2 sub-parts, parts 4 and 5 are undivided.
Whereas in Lasciar Vivrare v.4, only a selection from the large amount of produced sound material was used, and a rather complex route through the family tree was taken to define its large form, in Lasciar Vibrare v.5, all produced material was used and the route through the family tree was as simple as possible: from top to bottom.
Lasciar Vibrare v.4 was premiered at the Teatro Aberto in Lisbon during the Musica Viva Festival in September 2004.
Lasciar Vibrare v.5 was premiered at NDSM in Amsterdam during the festival “De verborgen planeet”.
family tree for sound production (sketch detail) 
family tree for sound production 
L.V. v.4 score page 1 
L.V. v.4 score page 2 
L.V. v.4 score page 3
Lasciar Vibrare v.4
year: 2004
duration: 15:30
tracks: 5.1
Lasciar Vibrare v.5
year: 2004
duration: 34:10
tracks: 8