Duration: 6:52

The Zephyr Quartet (Lydia Forbes and Jacob Plooij, violins; Elizabeth Smalt, viola; John Addison, cello)

Recorded at Felix Meritis Hall in Amsterdam, the Netherlands
International Gaudeamus Music Week 2005

____________________________________________________________________

Gravity Modulations explores shifts in "metrical gravity", which is the sum of all forces that tend to synchronize ("convergent forces") and asynchronize ("divergent forces") multiple concurrent layers of rhythm. These convergent and divergent forces are further divided into two categories: intrinsic and extrinsic. Intrinsic forces are imbedded in the music itself. Extrinsic forces encompass all elements from sources outside the music. Examples of intrinsic forces include overall rhythmic complexity, the prominence of certain layers compared to others, the presence of resynchronizing devices, etc. Typically, higher levels of complexity correlate to stronger divergent forces. Examples of extrinsic forces include the training of performers, their innate rhythmic abilities, the amount of time they rehearse, etc. Normally, higher levels of training, more acute rhythmic sensibilities, and more rehearsal correlate to stronger convergent forces.
For example, let us suppose that two intermediate flute students are instructed to play a simple piece together, but one is to perform it at MM quarter = 120 and the other is to perform it at MM quarter = 118. Started simultaneously and performed correctly, these parts should immediately begin to phase. However, this exercise has an overwhelmingly convergent effect that our hypothetical students could not likely resist. They will probably synchronize, if they manage to phase at all. Now, let us suppose the same exercise is proposed to two veteran interpreters of Steve Reich's phase pieces. Their background provides an extrinsic divergent force that may balance the convergent tendencies of the exercise, and coupled with sufficient rehearsal (another extrinsic divergent force), may result in a neutral metrical gravity. In other words, they can play the exercise correctly.
Metrical gravity is present in every performance of music involving two or more human performers. In Gravity Modulations, I simply recognize these forces and use them as compositional resources.