On Fri, 30 Jun 2000, Laurie Griffiths wrote:
> "Inversions" in genetic would correspond to "variations" in music
> e.g. turning the descending scale
> [K:D]e2d c2B
> into
> efe dcB
> or turning the long note A3 into the twiddley version A^GA
> on recorder and then turning that into ABA for fiddle.
So a tune could actually evolve that way. A few long notes are replaced by
a "gene substitution" with a sequence of notes to make a the tune more
interesting. And then a musician could get the idea to play some of them
in the opposite order, and we get an "inversion"
>
> Something that is in music but (I think) not in genetics is that
> some notes are more important than others.
And if one try to measure similarity just by sequence number, not taking
into account that a measure could have been pushed forward by an
"insertion", one would get utterly wrong
> In all of the above cases "the bones" of the tune are the same, they are
> just fleshed out differently.
We had a discussion on Gore/Breathnach theme codes a year or so ago. Those
codes are only using notes *on beat*. Solves a lot of those problems, but
I suppose it would not be able to take into account "translations" and
such things.
Interestingly, after the discussion on Gore/Breathnach codes I phoned up
librarians and archivists at music libraries/archives here in Sweden to
find out how they did this. I got a reprint from one of them:
Jan Ling and Margareta Jersild, 1965. "A method for cataloguing vocal folk
musik". Meddelanden fr�n Svenskt Visarkiv 21
The method is like a frequency distributions of notes, or rather the
percentage of the tune's total duration which is spent on each scale step.
The procedure was roughly this:
1. Transpose the tune such that the keynote is C
2. Count the occurence of each note and their lengths
3a. The frequency distribution is then translated into a code which can be
used looking things up in Svenskt Visarkivs catalogue. Cannot recall
how it is calculated
3b. Write a graphical representation of this as notes, letting the length
of notes represent the frequency
The authors claim that this "spectral analysis" of tunes offers an
excellent methods for finding similar tunes. It is sort of related to the
methods you were thinking of, Laurie.
Sigge
> Laurie Griffiths
> http://www.musements.co.uk/muse
> where you will find music notation software for PCs.
> ----- Original Message -----
> From: Sigfrid Lundberg, Lub NetLab <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Friday, June 30, 2000 12:24 PM
> Subject: Re: [abcusers] ABC, AHC, Do-Re-Mi
>
>
> > On Thu, 29 Jun 2000, John Walsh wrote:
> >
> > >
> >
> > ...
> >
> > > 3) Measure the (signed) distance of each successive note
> > > above/below middle C. Form a vector of these, (v(1),v(2),...,v(n)).
> > > Think of this as a function for the moment: v(t), t=1,2,...,n. In order
> > > to make the result independent of the key, subtract the (weighted) mean
> > > value from each v(i), and call the resulting vector V.
> >
> > As Mark notes in another mail, this would not make it independent of
> > key/pitch. The distance has to be measured in semitones from the tonic,
> > not from C.
> >
> >
> > > (4) Choose an integer k <= n, and find the best
> > > weighted-least-squares approximation of V by a kth order polynomial in
> t.
> > >
> > > (5) Compare two tunes by measuring the distance between their
> > > polynomials.
> >
> > Isn't it easier to use the squared distances between matching pairs of V?
> > You don't need the polynomials to measure the distance. However, there is
> > more to simililarity than this. I like Phil Taylor's protein metaphore,
> > since tunes evolves somewhat like proteins.
> >
> > There will be
> >
> > deletions: a segment of notes is removed.
> > insertions: a segment of notes is inserted
> > duplication: a segment of notes is repeated
> >
> > In genetics we also have inversions, but I reckon they are extremely rare
> > in music. The protein software is capable of recognize similarity, even if
> > events of these kinds have occured. Given a database might even be
> > possible to find a "source tune" from which a segment has been taken for
> > inserting it in a "target tune".
> >
> >
> > Sigge
> >
> >
> >
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