Tetrachord


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tetrachord

[′te·trə‚kȯrd]
(acoustics)
The basis of a variety of ancient musical scales, consisting of four notes, with an interval of a perfect fourth between the highest and lowest notes.

Tetrachord

 

in music, a succession of four pitches contained within the limits of a fourth. Tetrachords were the basis of musical modes and of the entire scale in ancient Greek music. The Greek names for diatonic tetrachords, just as the names for the corresponding modes, are still used in modern music theory, but they refer to modes with different interval structures.

References in periodicals archive ?
Documentary evidence exists in the famous postcard Carter wrote to a Boston music critic; both tetrachords are notated, their "all-interval" properties demonstrated, and Carter states that both tetrachords were used in both the First and Second Quartets.
At this point I show the student on the keyboard how to move around the circle of fifths using the tetrachords before drawing it for them, relating the key signatures as I go.
The tag "secundum Guidonem" may have signaled for the Bergamo 21 redactor simply a theory of mode more conventional than Marchetto's, and he here sets up a dialogue between old and new: modal theory based on final and range on the one hand ("Guido"), or on species of pentachord and tetrachord on the other (Marchetto).
It was necessary to have free circulation between the notes and their subdivisions, between the kinds of tetrachords, between the genera, between the systems, and between the echoi--hence the need for a sketch of the in-time structure .
At about this time, Zaragoza continues, Falco reached Madrid with his tetrachord and informed the Jesuit that it had been used very successfully the previous year (1674) in Valencia to divide the octave into 12 equal parts.
The author favors tetrachord structure for several reasons:
8) Jonathan Bernard relates this function to the composer's "deliberately global" use of smaller pitch sets--for instance, the systematic inclusion of all possible trichord types in the Piano Concerto, all possible tetrachord types in String Quartet No.
The chromatic tetrachord contains the essence of both major and minor tonalities in any particular key (it is a combination of 'melodic-' and 'harmonic-minor'), and its outer notes emphasize the tonic and dominant of the key: the [flat]VI-V movement is the ideal preparation for a dominant pedal, and is often used to set up the overall progression [flat]VI-V-I.
In two-thirds of these eight-bar periods the fourbar bass line ostinato consists of the descending tetrachord G-F-E-D, first plain, then varied in harmony, melody, rhythm and register.
The word (one unconvertible word in Greek Character) appears the papyrus remnants provide little intelligible context for it we can be confident that musical technicalities are still in play, in view of the indubitable reference to a tetrachord or tetrachords in the next line (the surviving letters are (one unconvertible word in Gre
Schoenberg's Klaviersuite, op 25, in which the HCAB motive appears as the final tetrachord of the prime row, is a much more likely model for "Simbolo.
In the C major exercises the semitone will always be mi-fa, but it will occur sometimes in the beginning, sometimes in the middle and sometimes at the end of the tetrachord.