I was recently reading the wonderful exchange (scroll down to the Dec. 6 entry) between pianist Jonathan Biss and Brentano Quartet violist Misha Amory about the similarities between the late piano sonatas and string quartets of Ludwig van Beethoven when I came across one of those ideas that I’d never thought about on a conscious level before. Some of Beethoven’s most profound transitions take place in unison passages (where all of the instruments play the same pitch). The amazing transition to the beklemmt section of the Cavatina of his string quartet Op. 130 is a prime example.
You can hear the big moment about 4:10 into this clip featuring the inimitable Guarneri Quartet:
It got me to thinking, what exactly is so right about using a unison in these sorts of situations? I think that it boils down to the fact that in the harmonic language of Beethoven’s time, there were a usual way that chords would resolve – even if they resolved unexpectedly, that was, in some sense, to be expected. The composer could either meet or defy expectations. When the ear is presented with a unison, the harmonic possibilities are quite simply completely open. And, much like the pedal point in a Bach organ prelude and fugue, or in the score to a horror movie, the unison focuses our attention to a very fine point – there’s only one pitch to listen to, and our brain very badly wants to know what is going to happen next. It’s classic literary practice – set up expectations, toy with your audience, make them watch your left hand when you get ready to produce the dove from the right hand. One more reason that Beethoven is such a genius.