Polychords – Creating Suspense and Tension

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Polychords

Photo by Marius Masalar

This post was brought to you in collaboration with our partner site Behind the Score. Discover the Harmony Secrets of Modern Film and Video Games.

Introduction and Polychord

Our next section explores a few ways to create uncertainty and suspense in music. There are many quick-and-easy orchestration tricks, including high-string sustains, tremolos, timpani rolls, designed sound effects, and more. However, we begin by focusing on Polychords. Countless films and video games employ this harmonic technique to evoke tension. Compared to the faster and easier ways of creating suspense, polychords add more depth, complexity, and weight to the music.

polychord combines two or more chords at once, typically with one stacked on top of the other. Our scores use the conventional “fraction” notation to indicate how chords are stacked within a polychord. For example,  signifies an A♭ Major chord stacked on top of a D major chord (see Fig. E).

Fig. E

The triads within polychords may be inverted, rearranged, and so forth. In Fig. E, both triads use wide “open voicing” (as opposed to closed voicing). The upper triad (A♭Maj) interlocks with the lower triad (DMaj). In other words, the E♭ from the top chord is below the F# from the bottom chord).

Neighboring Chord Tones

We find that polychords create suspense effectively when the chord tones within them are neighbor tones. For instance, compare the chords tones of A♭Maj and DMaj in Fig. E. The notes D and E♭ are a half-step apart (and may be inverted to major 7th or minor 9th intervals). The same is true for the notes A♭ and A. These dissonant intervals within a polychord create tension and anxiety for the listener. Let’s explore this concept in our next piece. Below is an example we’ve created using polychords to evoke suspense and tension.


Suspense & Tension with Polychords #1 

This example begins with a dismal mood that culminates in turmoil. We composed the piece solely using the polychord (see Fig. F). We chose the chords A and F7 since they have some neighboring chord tones: C-C♯, E♭-E, and E-F. The two chords also share the common tone A, which helps them blend well together. At times, we use enharmonic equivalents in our score for ease of reading.

Fig. F

Analysis

Lower register winds/strings step up from D♯ (or E♭) to E before landing on C♯ in the next measure (). A reedy, murky low bass clarinet doubles low strings, adding a sense of suspicion and anticipation. Tremolo strings drive up the energy in m. 2. The violins and viola span over an octave, creating a resonant harmony in the mid-register ().

Measure 3 brings a menacing shift in tone with the addition of brass, timpani, high winds, and vibraphone. The bass drops dramatically to a low F, supported by a low timpani roll. The horns fill the mid-register with a consonant interval (C♯-A) and dissonance (E-F, ). Piccolo and flute add light support up above. Notice the piccolo E♭ fighting with the horn E two octaves below, another example of a minor 2nd inverted and widely spaced.

Vibraphone plays a repeating pattern consisting of minor 2nd intervals (C-D♭ and E-F, ). The melody is a bit like a musical tesselation. Since the pattern lasts for six notes, it does not repeat at the start of each beat (only four “sixteenth notes” per beat). The rhythmic feel of the vibraphone creates a sense of disorder and chaos, which is advantageous to us in this musical situation.

As the piece concludes, all instruments crescendo, building to a climax. The swell in volume brings out several features: the minor 2nd in the horns, the string tremolo texture, and the threatening roll of the timpani. Yet, we can organize the chaos by structuring the harmony around a polychord. This way, the music sounds intentional rather than random.

Additional Resource

💡 Theory in Depth) Upper Triad of a Polychord
Vincent Persichetti (composer/educator) offers a more nuanced approach to building polychords. In essence, when choosing a suitable upper triad, he considers the overtones of the lower triad, voicings, and how they affect overall resonance.He outlines a process for finding all possible upper chords for a polychord built with major triads. In the example below, he has chosen to put his lower triad in second inversion, which he finds more harmonically resonant. In his view, the intervallic spacing of a second inversion chord (a third interval on top of a fourth) matches a portion of the overtone series more closely than other inversions. “The upper triad of a polychord depends upon its proximity to the overtones of the third and fifth of the lower triad for resonance ..(omit).. [An] inventory of major-major polychords may be made by building the upper major triads on the notes of a cycle of perfect fifths that begins with the bass note of the bottom six-four chordal unit. The triads are added, in turn, to the bottom six-four chord, creating a rising order, based upon the cycle of fifths, which places the chords in a natural sequence of decreasing consonance and increasing dissonance.*” 
In short, the upper triad roots are ordered by ascending 5ths, starting with the bottom note of the lower triad. If we employ this theory to the (F triad+A triad) polychord used in Ex. 5-9-A, an A Maj triad is the 4th harmony in the cycle of perfect 5ths from a C triad (C→G→D→A). The chord C was chosen here since it is the bass note of F Major 2nd inversion (F/C). 

Upper Triad of a polychord (P.138, Twentieth-Century Harmony, Persichetti,  W.W.Norton&Company)

This is an excerpt lesson from the [STUDY PACK] Various Genres – Movie Ident, Spooky, Suspense, Crime Drama, Etc. Complete editions of video lessons, music scores (PDF), score analysis (PDF), and HD music examples used in this lesson can be viewed here.