[PD] more Fibonacci

Chuckk Hubbard badmuthahubbard at gmail.com
Fri Aug 11 16:58:03 CEST 2006


On 8/10/06, Charles Henry <czhenry at gmail.com> wrote:
> > I don't think 5-tone equal temperament is a substitute for the
> > pentatonic scale.  The pentatonic scale is made up of decidedly uneven
> > intervals.
>
> Yes, it's true.  They're two different things.  I disagree with the
> John S. Allen article that there's a connection between the pentatonic
> scale, diatonic scale and fibonacci sequences.  One is a subset of the
> other.  We're not get better approximations of just intonation as we
> move from one to the other.  I'm saying that we get better and better
> approximations, in a monotone decreasing series, as we move through
> the equal tempered scales using the fibonacci sequence.  I'd trust in
> the just intonation system, if it weren't so hard to modulate keys.

You'd get still better approximations with 1 million divisions of an
octave.  Is there any relation between integer ratios and logarithmic
divisions based on the Fibonacci sequence?  Seems like that's really
the only question.  I guess I'd be hesitant to say no, with it phrased
that way.
I like just intonation because there are so many more possibilities to
modulate; which lend themselves better to some instruments than
others, of course.  My JI Sequencer was an attempt to make this more
intuitive, for non-real-time composition.  (I intend to clean it up
and post it soon, hopefully today)
Toby Twining's 13-limit vocal works are the best JI I've heard:
http://www.justintonation.net/soundfiles.html#twining
The top set of examples.  I think the Kyrie is the best, but the
Sequence I, which is actually a Dies Irae, is pretty haunting (not so
much in this exerpt).

> The small-numbered ratios of frequencies create consonant intervals,
> because of the harmonic overlap (when using a harmonic series).  These
> are the local minima of dissonance as a function of interval.  I think
> that what we hear in these more outlandish tuning ratios are only
> approximations of the small-numbered ratios (don't ask, how small is
> small-numbered? cause I really don't know...It's pretty hard to tell).

What do you think about the 4/3?  At times this interval was forbidden
in counterpoint as a dissonance, and obviously the 4th harmonic of the
higher tone and the 5th of the lower clash, and even more so the 5th
of the higher with the 7th of the lower.  Yet it is a small-number
ratio, and most consider it consonant, if only as a suspension.  Then
again, chords built entirely of perfect 4ths are common in jazz, and
not at all unsettling (I would call this a Law of Pragnanz situation).
Harry Partch insisted the ear could adapt to arbitrarily high prime
ratios.  He only went as high as 11, and that tends to be pushing it
for most people.  7 is essential  though, IMO.  I use 11-derived
intervals, usually only at the higher end of a chord.
At any rate, insisting that all scales are built on perfect fifths is
a regression to Pythagoras.

For Islamic theorists, supposedly al-Farabi described positioning the
frets so that, for instance, one fret goes at 8/9 of the string, the
next at 8/9 of the remaining length, and the next one halfway between
them.  Halfway between 72/81 and 64/81 is 68/81, or 81/68 of the
frequency.  Definitely not small, but easy to place, and maybe having
some of the interesting quality you're talking about with a distinctly
Arabian sound...

> There's something strange about those mistuned harmonics that gives an
> instrument its richness.  I know that Plomp studied this back in the
> 60s "Beats of mistuned consonances" in JASA.  When we detune two pure
> tones away from a small-numbered ratio (like 3/2), there are beats,
> that do not correspond to difference tones, cubic differences, or
> other distortion products.  It's not a physical phenomenon, not part
> of the cochlea, but something to do with the brain and how it groups
> the harmonics together (could possibly be related to stochastic ghost
> resonance, mentioned by Chialvo in Chaos, which has to do with the way
> that harmonic ratios of impulses sync up along single neurons)

Is this related to how they say we hear certain difference tones even
when the real tones are isolated in either ear?   Or maybe just
coincidence.
A lot of people say that just intonation "lacks the energy" of 12-tet,
and JI enthusiasts counter that 12-tet lacks the restfulness of JI.
Anecdotally, Western theorists pushed for more and more modulation
(intellectual stimulation?), while some Eastern music still is happy
to rest on one chord for a long time, or to keep one tonic drone
through a whole piece.  Ben Johnston suggested tuning temperament was
behind the drug addiction and restlessness of so many jazz and rock
musicians, lol.

>
> What is it with people and their morbid fascination with fibonacci sequences?

For all I know you only said that for my benefit, lol.  I'm not a
number expert, but I actually find the plain old prime series more
mysterious.
-Chuckk




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