source file: m1587.txt Date: Thu, 19 Nov 1998 17:01:54 -0500 Subject: Re: TUNING digest 1584 From: "Paul H. Erlich" There is one thing about the diatonic and pseudo-diatonic scales I mentioned which seems important but is not shared by other similar scales such as 19 out of 22: in the scales I mentioned, a given consonant interval is always approximated by the same number of scale steps. This seems like an important grammatical feature without which the sense of the scale as a fixed melodic basis could be very difficult for a composer to convey. Stronger requirements such as Rothenberg propriety (which requires that a given number of scale steps always subtends an interval smaller than the smallest interval subtended by that number plus 1 scale steps) seem less useful as they exclude such common scales (such as the Pythagorean diatonic) from consideration.