Strophe was commissioned by Colin Currie, for vibraphone and the Miró String Quartet for their 2013 U.S. tour. Since Colin asked me to specifically write for vibraphone, I wanted to base the piece on his playing, of course, and the simple idea of all material stemming from the vibraphone itself. The most basic characteristic of the instrument is its ability to resonate, and this can be manipulated by the use of the sustain pedal, similar to that of a piano. The other element, and probably the most important for me in this piece, was the overtone frequencies of the metal bars.
Before I started though, I had to consider the problem that has come to be expected by all percussionists – no two instruments are ever the same. This can be seen as an issue for the composer, but it’s what keeps percussionists unique in their approach to performance. When dealing with metal percussion instruments, the tunings are always different from one instrument to the next because of the alloy and chemical makeup. But there are some overtones that are generally consistent on all instruments. I wrote my piece on two instruments – one older with bars made of bronze and steel and a modern instrument made of hard, light aluminum alloy. Generally I prefer the older instruments because the fundamental pitch is stronger and the first overtone all vibes are tuned to (fundamental two octaves higher) helps the technique of playing harmonics. All of my pitch material comes from the overtones of the metal bars, which ring differently depending on the register, type of mallet, and dynamic played. When played in succession, as in the opening lowest F natural, the overtones are most rich and obvious. The overtones I based my structures on are, the 8th (F two octaves higher), 10th (A), 15th (E), and 17th (F-sharp). Since I was expanding the pitches of the vibes above the instrument with the help of the quartet, I also wanted to extend below. To do this I created a series of “undertones,” by inverting the overtone pitches with the F natural as a center pivot.
The title Strophe is taken from the original Greek strophi (stro-fee), meaning the act of turning, to bend, to twist. With the induction of overtone frequencies in combination with the quartet, there is always a sense of friction, which gives rise to motion.
The piece is in an arch form in three short movements. In the first movement the vibes initiate all activity, while the quartet reacts, pressing up against and resisting the motion of all elements. As if two separate forces, they constantly rub right up against each other, moving over and through surfaces, expanding above and below the range of the vibraphone.
The second movement is an interlude, in static focus on the natural vibrations and resonance of the metal bars. The quartet mimics the vibrations in slow motion with the use of changing tremolo speeds – as if inside the bars. Then through the use of colored bow changes, vibrato speeds, and microtonal tunings, they create a type of viscous friction moving relative to one another, only to change paths when coming into contact with the bowed vibes.
In the third movement all material comes from the quartet, but, already influenced by the vibes by this point, they translate the higher close frequencies into octatonic scales. This fast and frantic rondo-like movement, is at first echoed by the vibraphone’s use of the vibrato motor at different speeds and by the end of the piece, this resonance eventually takes over. The frictional force and contact between the elements induces constant change, transforming into a new stable and unstable form always emerging.
— Joseph Pereira