source file: m1418.txt Date: Sun, 17 May 1998 15:59:16 -0400 Subject: Tetrachordal thinking From: monz@juno.com (Joseph L Monzo) [Neil Haverstick:] > Here's a question which I was originally going to post > privately to Chalmers, but thought I'd air it out here for > maximum response; why are scales formed by tetrachords in the > first place? I've read about them for many years, and all of a > sudden I realized that I don't know the fundamental reason behind > their origin. Any thoughts are surely appreciated....thanks... > Hstick There are two main reasons that scholars have accepted for the emergence of music theory in a system of tetrachords: 1) Tetrachords provide the smallest _diatonic_ interval-structure that repeats. In other words, in a diatonic scale, that is, one with steps of the sizes "tone" and "semitone", the interval structure of the four notes within a "perfect 4th" will contain one "semitone" and the rest are "whole tones". This is the smallest diatonic unit that provides a "semitone", and thus the unique smaller step which identifies the structure. In genera other than the diatonic, the tetrachord still encompassed the main identifying interval, be it a 6/5 in the chromatic, a 5/4 in the enharmonic, or some other ratio of a "3rd". 2) Ancient Greek was a tonal language, where the _pitch_ of a vowel affected its meaning (like modern Chinese). It is assumed that during poetic speech, the "melody" of the phrase covered approximately the range of a "4th", thus this became the important unit to the Greeks. Joseph L. Monzo monz@juno.com 4940 Rubicam St., Philadelphia, PA 19144-1809, USA phone 215 849 6723 _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]