The Diminished Triads And Their Role In Modulation

The unusual power of the diminished triads emerged earlier in the history of music than the role they eventually played in modulation and the extension of tonality. Bach depicted the evil character of Barabbas in the St Matthew Passion by having the chorus sing his name to a diminished triad. Haydn, in the choral movement known in English-speaking countries by the Latin text Insanae et vanae curae, alternated the key chord of d minor with the altered dominant 7th containing notes 2, 4, 6♭ and 7#, to dramatic effect.

The diminished triad comprises four adjacent minor thirds. Like the augmented triad that is based on Major thirds, it is symmetrical and inverts as itself. There are thus three diminished triads available:

Ti/Re/Fa/Si

Doh/Ma/Fi/La

Di/Mi/Soh/Ta

Each of these three triads can be spatially situated within the gestural framework of Harmony Signing to one of the three Primary Triads. The sign for the diminished triad is produced by crossing the index fingers of both hands centrally in front of the body: Ti/Re/Fa/Si is below the waist, and represented by the sign _x; Doh/Ma/Fi/La is at the same horizontal level as chord I, represented by x; Di/Mi/Soh/Ta has the hands in front of the face, represented by ^X. These three sign positions are designated

_x x ^X

(A)

(B)

(C)

An excellent means of testing participants’ discrimination between these positions, and the precise tuning on which they depend, is to attempt the following progression:

The diminshed triads can play a salient and expressive role in modulation (see also Short cuts to alternative modulatory pathways). Here are two examples:

(A)

(B)

And here are two commencing in the minor:

(C)

(D)

Experienced signers and participants will be able to devise harmonic progressions that combine the diminished triads with other Harmony Signing procedures so as to compose and improvise an almost infinite array of musical discoveries modulating to every possible key, both Major and minor.