Polychord (harmony)

In harmony , the Greek-English made-up word polychord (from the Greek poly… many and chorda , string, which in modern English has the meaning “chord” in the form chord ) describes a sound composed of several chords .

Competing models for interpreting complex chords

The term is not without controversy, as there are serious delimitation problems. For example, the completely diatonic sixth note in G major, Cmaj9 # 11

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can be interpreted as a combination of the triads in C major and B minor (in the traditional German spelling: B minor), i.e. as a polychord:

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In terms of hearing, however, this interpretation is not mandatory. Argues against the back with respect to a possible G major tonality that the chord represented, for example, in Modern Jazz - arrangements of musicians such as Duke Ellington or Dizzy as tonic chord in C major is used. However, the same argument could be made against the interpretation as a polychord: Despite all the complexity, the sound is related to only one and not two tonal centers. The reason for this lies in the so-called combination tones, which occur with multi-sounds (intervals or chords) and have a reinforcing effect on certain tones of the multi-sound. The most amplified tone is perceived by the ear as the fundamental tone. For example, in the interval c'-f ', the combination tone f occurs, so that f' - and not c '- is perceived as the fundamental tone of this interval.

In the chord symbol writing of jazz and the styles related to it, the convention has prevailed to notate a polychord in a way that resembles a mathematical fraction : the "upper" sound is in the "numerator", the "lower" correspondingly in the "denominator" . This notation stems from the fact that on the piano , on which such chords can practically be fingered in full voices, the two sounds are distributed exactly in this way to the left ( bass ) and right ( treble ) hands.

The chord symbol for the sixth note shown above is in polychord notation

${\displaystyle {\frac {Bm}{C}}}$

In any case, the definition of the polychord already shows that it is a very complex sound; in the simplest model described, it is a combination of two triads , i.e. six-part. The polychord notation is also often used for seven or eight-part chords:

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is a seven-part chord consisting of a dominant seventh chord over C and a D major triad. The chord symbol reads in polychord notation or in function- harmonious conception C13 ^{# 11} . The polychord notation proves to be particularly helpful when layering unrelated diminished seventh chords , where eight-part sounds can result for which traditional chord symbols no longer have a common notation: ${\displaystyle {\frac {D}{C7}}}$

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Here the polychord symbol is still the clearest and, comparatively, the fastest legible representation of this highly complex, quite dissonant sound, which is difficult to intonate in an ensemble . ${\displaystyle {\frac {D^{o}7}{C^{o}7}}}$

For a jazz theoretical interpretation see: Upper Structure . It is typical of the multiple chords in jazz that their voices are not mixed by crossing and interlocking, so the function of the chord is clearly that of the lower chord. In contrast to a functionally harmonically interpreted chord, they do not allow all reversals. In the example above, the D major sound should only begin gradually above the last played chord tone of the C7 chord. Its primary definition is that of a triad over a tritone, i.e. a dominant seventh chord. Many jazz pieces, arrangements or boogies etc. end on the dominant seventh chord with sounds superimposed. The other forms are then derived by playing triads over chords with other functions. Upper structure in the narrower sense are then complete structures in which the upper structures are not included in the scale or tonality of the basic sound.

In musical practice

Because of their tonal richness and complexity, polychords, as already indicated, are seldom played in full even on the piano. In ensemble playing, they are ideal for dynamic Tutti -Passagen so that, for example, the final chord of modern Big Band - Arrangements , as in the style of Bob Brookmeyer , Gil Evans and Maria Schneider often a Polychord. Another big band known for their perfectionist work with such complex harmonic structures is the orchestra of Thad Jones and Mel Lewis .

The "hard" sound quality resulting from the dissonant character of most polychords is also suitable for percussive, strongly rhythmic ensemble passages, for example in Igor Stravinski's famous ballet Le sacre du printemps in 1913 , for example in the episode "Danse des adolescentes" .

The designation of polychords as “ bi- ” or “ polytonal chords” can be traced back to the analysis of works by composers of the classical modern era (such as Claude Debussy , Béla Bartók , Charles Ives and Stravinsky) .

Simplifying models

Based on the principle of chord inversion , the concept of so-called slash chords (literally "slash chords") has been established since the 1970s . This is a method of achieving complex sound effects similar to polychords by the musician laying a triad over a bass note that is not part of the chord. The term slash chord comes from the typical notation for these chords, which could be, for example, C / C # and should not be confused with the fractional symbolism for polychords explained above. The main advantage of slash chords is that, due to their simpler structure, they can also be played in full on other harmony instruments than the piano (e.g. on guitar or vibraphone ).

criticism

Finally, it should be noted that the basis of all bi- and polytonality is disputed by many music theorists. Specifically, it is doubted that it is even possible for the best-trained tonal ear to hear two or more tonalities at the same time; rather, everything that can be interpreted tonally is related to exactly one bass or fundamental tone . It is therefore possible for a well-trained listener to analytically "listen through" even highly complex sounds like the ones described above, but not in the sense of two or more individual chords.

The basilar membrane in the human inner ear

This skepticism is supported by neurophysiology on an even more fundamental level : It can be assumed that the human ear is not able to perceive two objectively simultaneous acoustic events absolutely simultaneously. Rather, the auditory impressions are processed in the brain very quickly one after the other . Strictly speaking, what is heard separately is only "put back together" in the relevant areas of the cerebral cortex .

The fundamental criticism of the prerequisites of bitonal concepts can ultimately not justify an aesthetic value judgment about the work of the many and stylistically very different composers and improvisers who were inspired by the models described.

literature

• Diether de la Motte : Harmony (= dtv 4183). 10th edition, joint original edition. Deutscher Taschenbuch-Verlag et al., Munich et al. 1997, ISBN 3-423-04183-8 (first edition 1976).
• Anthony F. Jahn, Joseph Santos-Sacchi (eds.): Physiology of the ear. 2nd edition. Raven Press, New York NY 2001, ISBN 1-56593-994-8 .
• Andy Jaffe: Jazz Harmony. 2nd edition. Advance Music, Rottenburg 1996.