source file: mills2.txt Date: Fri, 16 May 1997 01:59:04 +0200 Subject: Re: Structure in JI From: Brian Lee 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