JustBeeps    by Phil Burk

Written using JForth Professional V2.0

Public Domain.  Freely Redistributable.

JustBeeps demonstrates the use of the Audio and Timer devices.
It plays a series of notes, that are related to each other
by just intoned intervals.

To hear the program, from the CLI, enter:

	JustBeeps

To compile and run the program, enter JForth as you normally would,
then enter:

	cd :JustBeeps
        include JustBeeps.f
        JustBeeps

What is Just Intonation versus Equal Temperament?

Most western instruments are tuned in a 12 tone equal temperament.
Every note in this scale is higher than the previous one by
the 12th root of two.  If you go up 12 notes, you have gone up
by 2**(12/12), or 2, which is an octave.
Since all intervals between adjacent notes are
equal, you can play equally well (or equally poorly) in any key.
Bach, Lanfranco, and others developeded this tuning to make it
easy to change keys during a piece, and also so you can play
pieces in different keys without having to retune the instrument.
This tuning was designed more for convenience then anything else
and is basically a kludge.

Non-western instrument, eg. Indonesian gamelans, Indian sitars,
etc. are typically tuned very differently.  They are generally
tuned based on a just intoned system, with some deviations to
get a more lively sound.  A just intoned system is one where
the note intervals are based on ratios of whole numbers.
A fifth might be exactly 3/2 higher in frequency than
the tonic.  A third might be 5/4 higher in frequency.
This can often give a much sweeter sound then equal temper.
It can also sound "out of tune" to western ears.

In this simple program, there is no tonic.  Each note is some
whole number ratio higher or lower then the previous note.
Each interval will sound fairly "nice" but the tuning
will sound like it is wandering all over the place.
The program will select two whole number to make a ratio
and calculate a new period for the note.  If the period
is out of range it keeps trying till it gets one in range.
It prints each pair of numbers it trys, then prints the final
period.

I hope this simple example program will encourage you to
experiment with the Amiga Audio capabilities.  If you are
interested in experimental music you may want to get HMSL,
the Hieracrchical Music Specification Language.
This is an experimental object oriented composition language
available for purchase from Frog Peak Music.  For information
write:

	Frog Peak Music
	P.O. Box 1051
	San Rafael, CA
	94915

HMSL has an extensive toolbox for experimenting with different
tuning systems, MIDI, algorithmic composition, and interactive
performance.