controlling drift in adaptive JI

> [John deLaubenfels, TD 497.1]
> There would be danger when a piece goes through an extended
> passage very distantly modulated from tonic (or whatever
> note is grounded), that tuning would drift aimlessly and
> irritatingly. In general, though, I really like the idea
> of nailing down one pitch and letting the others find
> themselves according to the harmonic needs of the sequence.
> I'll play with adding that capability to the program, and
> should have some trial results by Monday, if not sooner.

> [Christopher Chapman, TD 499.7]
> This may sound silly, but would it help to have the equivalent
> of a set of "open strings"? For example: on my violin the
> open strings are (usually): G D A E. I don't have to play
> the strings open at all, but I can play them occasionally
> to make sure that my fingerings haven't drifted too far.
> Maybe you can chose a small set of grounded pitches that
> are the equivalent, rather than grounding all of them or
> only one of them.

Christopher's approach is an interesting one.

There are two others I plan to incorporate in my JustMusic
software: allowing the user to specify the 'root' of the
target of a modulation, and using an algorithm derived
from Partch's 'three observations' concerning his idea
of 'field of attraction' (see Partch 1974, p 182-183).

Paul Erlich's 'harmonic entropy' concept is related to
Partch's, and could provide another approach. Paul?

REFERENCE
---------

Partch, Harry. 1974.
_Genesis of a Music_, 2nd edition.
Da Capo Press, New York.

-monz

Joseph L. Monzo Philadelphia monz@juno.com
http://www.ixpres.com/interval/monzo/homepage.html
|"...I had broken thru the lattice barrier..."|
| - Erv Wilson |
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Joe Monzo wrote,

>There are two others I plan to incorporate in my JustMusic
>software: allowing the user to specify the 'root' of the
>target of a modulation, and using an algorithm derived
>from Partch's 'three observations' concerning his idea
>of 'field of attraction' (see Partch 1974, p 182-183).

>Paul Erlich's 'harmonic entropy' concept is related to
>Partch's, and could provide another approach. Paul?

Joe, I have no idea how any of these would be used to control drift, least
of all harmonic entropy.