Two versions of this concerto are available:
This double concerto is a hybrid of styles and techniques. It combines concepts and techniques originating as far back as the 17th Century with rhythms, harmonies, textures and processes of recent music. Movement titles relate to certain prominent techniques or concepts and also hint at how the past often informs new, or future developments.
The energetic first movement begins with a process of expansion: a motoric repetition of a rising and expanding series of eighth notes. It expands because more notes are continually added to the pattern and because intervals between notes get bigger. The two keyboards then add dialogues of contrasting rhythms and harmonies over this expanding ostinato. One notable aspect of those dialogues is that they often play in different note groupings: the fortepiano in 3s and the harpsichord in 2s. The result is a lively and playful dialogue between rhythms, meters, harmonic colors and instrumental forces.
As the title suggests, echoes are important in this slow movement. The two keyboard players introduce various melodic strands that orchestra players then quietly repeat. Because earlier patterns continue as new ones are added, the textures become more complex over time. Waves of such texture ebb and flow while the keyboard players elaborate in freer and more expressive ways. Occasionally, dramatic accelerandos lead to mildly tragic climaxes. Some are expressive harmonies shared between the keyboards in fast echo-like dialogues, while others are orchestral climaxes of “controlled aleatory” (busy texture made of many strings playing fast, but not together). The result is a sombre and expressive middle movement.
… to a future…
The upbeat final movement could technically be called a rhythmically expanding and contracting modulating chaconne (chaconne being variations based on a repeating chord progression.) The fortepiano begins quietly, playing the chords simply and in a relaxed regular rhythm. When repeated by the harpsichord, some chords are given shorter durations while others become longer. Finally, when the orchestra plays the chords, a quirky syncopated rhythm based on expanding and contracting note values is heard. This rhythm then continues throughout most of the movement. While the chords are always used (sometimes appearing in different keys), the rhythm disappears during the keyboards’ duo cadenza. In most other places, though, it continually repeats like a Medieval isorhythm that’s been updated for modern ears.
For the original version (fortepiano and harpsichord), a small string section is recommended. Just be certain there are enough players to cover all divisi parts in the second movement! When available, the use of Baroque strings is also recommended. Finally, the keyboards may need amplification, especially when modern strings are used. When performing the version for modern pianos, conductors should feel free to use larger modern string sections without amplifying the pianos.