[sdiy] Generating acyclic waveforms?

[karl dalen]

Does that also apply to bores/tubes with dents on inner surface, so that pitch changes and also spectrum change who are solely generated by the air
pressure and not by shortening or lengthen the bore/tube by valves?

I happen to have a tube here that by blowing it can seamlessly go from
one pitch to another and in between create a kind of inharmonious wave.
Perhaps this are something else then stretched harmonics?

What about Twin T filter oscillator emulation band oscillation like in drums? Damped string model on skins?

KD

--- Den mån 2010-03-22 skrev Ian Fritz <ijfritz at comcast.net>:

> Från: Ian Fritz <ijfritz at comcast.net>
> Ämne: Re: [sdiy] Generating acyclic waveforms?
> Till: "Magnus Danielson" <magnus at rubidium.dyndns.org>
> Kopia: "synth-diy" <synth-diy at dropmix.xs4all.nl>
> Datum: måndag 22 mars 2010 06.36
> At 07:06 PM 3/21/2010, Magnus
> Danielson wrote:
> 
> >> You wouldn't see a significant effect like this in
> winds because the waves are longitudinal waves in air and
> therefore have negligible dispersion.  Additionally,
> driven systems such as winds excite coherent waves, so there
> can be no speeding up of specific harmonics over many
> cycles.
> > However, the end-impedance would allow for a similar
> effect, such that the resonance frequency of the overtones
> would not match up exactly with the integer multiples
> frequency-wise form the base frequency. To illustrate the
> impedance effect on a wind instrument...
> 
> 
> No. The played notes have harmonic spectra, because they
> are periodic.  (In mathematical terms this is known as
> "Fourier's theorem").  You are perhaps thinking of the
> resonances of the impedance curves, which are affected by a
> number of parameters, including the shape of the bore and
> end effects.  The art of making instruments is to try
> to get the two spectra to match reasonably well.  This
> is *extensively* discussed in Benade's book "Fundamentals of
> Musical Acoustics", chapters 20-23.
> 
> Ian
> 
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