Structure in JI

In answer to the question of how JI composers structure their music. The
strength of JI as a system is that the rational relationships between the
notes can be expressed in whole numbers whereas ET systems define the notes
logarithmically.

Please bear in mind that not all JI systems are the same. You can construct
a JI scale by taking a chunk of the harmonic series (what Partch calls
Otonality). You can take a mirror image of the harmonic series (what some
would call the undertone series) and an octave chunk of that becomes your
scale (Utonality in Partch's nomenclature). You can work in a tetrachordal
system or you can as Lou Harrison sometimes does work in free JI where you
just intuitively step around using a set of intervals rather than a fixed
scale.

As there are various JI scales, there are various ways of structuring. For
example, the higher the prime identity of the note (in relation to another
note) the greater the potential dissonance. So by looking at the numbers and
how they move you can get an idea of the relative dissonance or consonance
of a pattern without mentally calculating the exact interval. Eventually one
can develop a right-brained approach to number.

JI can't however let you play in anything like a key system (except that is
for what Ray Tomes calls Dynamic JI where the intervals get automatically
recalculated whenever you declare a new tonic). There are JI scales of more
than 12 notes to an octave where you can take subsets of notes according
their prime identity and these subsets (or spaces) have similar internal
structure, so moving from one harmonic space to another can give that gear
shift feel of changing key. But unlike ET you're not giving your spaces
arbitrary labels from the letters of the alphabet, with JI your space has a
numerical identity and that's what you call it.

Those are the sort of structural concerns that interest me at the moment.

Brian Lee

Received: from ns.ezh.nl [137.174.112.59] by vbv40.ezh.nl
with SMTP-OpenVMS via TCP/IP; Fri, 16 May 1997 03:06 +0200
Received: by ns.ezh.nl; (5.65v3.2/1.3/10May95) id AA03386; Fri, 16 May 1997 03:06:16 +0200
Date: Fri, 16 May 1997 03:06:16 +0200
Received: from ella.mills.edu by ns (smtpxd); id XA03384
Received: (qmail 26152 invoked from network); 16 May 1997 01:06:12 -0000
Received: from localhost (HELO ella.mills.edu) (127.0.0.1)
by localhost with SMTP; 16 May 1997 01:06:12 -0000
Message-Id:
Errors-To: madole@mills.edu
Reply-To: tuning@eartha.mills.edu
Originator: tuning@eartha.mills.edu
Sender: tuning@eartha.mills.edu