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Examples
Musical gestures can be produced on the beat or event scope but they
can also be part of melodic phrases, as articulations of combinations of
musical notes. Consequently a parameter for expression must be chosen
along, keeping in mind that changes developed, are either perceived
as mutations in duration or spectra. A mathematical expression or a set
of rules or probabilities give values that change always as
function of time. Examples of functions which provide a
variety of numbers for musical parameter manipulation in Physical Models are:
The random function
|
(1) |
which returns an integer greater than zero
and less than or equal to the given value n. This function is the
basis for creating Random Walks or different ways ordering
and sorting of a musical event.
The Henon Map:[7, Weeks, 1999]
|
(2) |
|
(3) |
is an example of a set of rules for generating periodic, quasi periodic
and chaotic signal which can be mapped to a set of N pitches in a
sequence of notes. Careful choice of values A and B manages the
behavior of the signal
The Restrepo Map: [6, Restrepo, 1997]
|
(4) |
is a result of Teager's filter and gives a periodic predictable region
plus a chaotic region. Values different to 0 and 1 and on the intervals
|
(5) |
can be mapped to rhythmic
and drumming patterns in addition to a sequence of pitches.
The Henon Map and the Restrepo map are two eamples of recursive
functions that can be mapped to midinote values using the following
normalizing function suggested by Craig
Sapp [3, Sapp, 2000]:
|
(6) |
Next: Results
Up: Parameter Manipulation for Composing with Physical
Previous: Expression and Random or Chaotic Behavior
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Created and Mantained by Juan Reyes