Measures of Turbulence(2006)
8 guitars (5 acoustic, 2 electric, 1 bass)
Boosey & Hawkes (Hendon Music)
San Francisco, CA
Guitarists including David Tanenbaum
Measures of Turbulence explores the sound of gonglike, harmonics in the two electric guitars, with melodic lines, ostinato patterns, and strummed chords in the classical guitars. The emphasis is on nuances of ensemble texture and rarely does an individual instrument emerge as a solo voice. One exception is the bass, which does not play for nearly half the piece, takes a leadership role for the first couple of minutes after it finally enters.
The work is not overtly turbulent or dramatic but rather deals with relatively subtle harmonic and rhythmic disturbances that don’t cause catastrophic fractures or upheavals in the music but rather contribute to a constantly evolving dynamic equilibrium. Having said that, I imagine that it is a matter of perspective; to the individual leaves on an Aspen tree the breeze is a violent disturbance while the nature lover on the path below witnesses a gentle shimmer. Similarly, for a group of guitarists performing a 15-against-8 polyrhythm, the sense of disagreement is quite dramatic, while the listener, hears a blended rustling.
A word about the electric guitar harmonics: For years I have used these multiphonics in improvisatory contexts but, until now, I have never asked anyone else to learn them since the finger must be placed very precisely in positions never used for ordinary playing which makes them difficult to notate and difficult to consistently reproduce. When executed properly each harmonic produces several, predictable pitches, which sound more like gongs than a guitar.
Perhaps these harmonics are the best metaphor for the role of perspective in Measures of Turbulence. In order to produce these multiphonic harmonics the string must quiver in spasmodic paroxysms, yet the result of all that turbulence is a stately, somewhat solemn sound.
Measures of Turbulence is fifteen minutes long. It was commissioned by the San Francisco Conservatory for the opening of a new facility and premiered on January 28th 2007 by students, faculty and alumni of the conservatory’s highly regarded guitar program, led by David Tannenbaum.
San Francisco Conservatory Guitar Ensemble/David Tanenbaum