[PD] Helmholtz Motion Verifier

Andy Farnell padawan12 at obiwannabe.co.uk
Sun Dec 12 10:55:20 CET 2010



A job for spectral tools I would guess. At the point
spectral flux hits a first minimum and autocorrelation
hits a first maximum, the string will be in stable
resonance. You could use something fast like
bonk or a schmitt trigger to time those from
the onset and get a measure of "how well" the note
was bowed.

Actually verifying that the thing is in stick-slip
Helmholtz motion is a different thing than looking
at the waveform, you need a stroboscope or very
high speed camera for that.

BTW if you have never seen the images of Prof Andrew 
Davidhazy there's plenty of string sequences there. He
kindly gave me some for my book cover.

ajf


On Sat, 11 Dec 2010 20:29:11 +0100
Ludwig Maes <ludwig.maes at gmail.com> wrote:

> How would one (and how hard or easy would it be) write a patch which
> does the following:
> Instruct the user to play a sustained note on the violin; then give
> feedback about how accurate Helmholtz motion is achieved; Could we
> measure how short the transient takes from nonHelmholtz motion to
> helmholtz motion? How about changing from a note on one string to one
> on another, ...
> Could we write a patch that trains the user to minimize install and
> end times for helmholtz motion and to somehow show a level of
> periodicity during the systaining period?
> 
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-- 
Andy Farnell <padawan12 at obiwannabe.co.uk>



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