Andor wrote:
> On 15 Okt., 18:16, Sampo Niskanen <spnis...@[EMAIL PROTECTED]
> wrote:
>> The simulation time scale, however, is quite short, so I don't
>> want a gust of wind to last the whole simulation duration (that
>> would effectively change the average wind speed).
> Ok, I see. I think I had a similar discussion with somebody here
> some time ago who wanted to use "pink noise" for audio testing
> purposes. He was also interested in generating series with PSD
> pro****tional to
>
> 1/(1+ K f),
>
> with a finite cutoff, going flat towards DC, and having the 1/f
> property for audible frequencies.
Another situation where a low-frequency cutoff would be desirable is
when the generating mechanism is intermittency. Some nonlinear
systems have an operating regime where the state grows very slowly,
until it crosses a threshold inducing bursty output, which eventually
returns the state to the slow region. If the duration of quiescent
intermissions is unbounded then the system can exhibit true low-
frequency divergence.
Now, feeding the intermittent signal to an allpass filter can turn
bursts into smoother oscillation suitable for modulating musical
quantities, like pitch. But we don't want that viola synth to sound
like an '80s Casio every now and then, so the intermission length
must not much exceed the effective length of the allpass impulse
response in this application.
I don't know if anyone has published on this in the musical context,
but here are two articles describing intermittent iteration
processes, one free and one not:
http://www.istia.univ-angers.fr/~chapeau/papers/psiplrc2.pdf
http://prola.aps.org/abstract/PRA/v31/i3/p1830_1
Martin
--
When he had finally achieved a position that
allowed him to say everything he thought, he
only thought of his position anymore.
--Gabriel Laub
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