Question: How do you create a natural and organic rubato? Somebody suggested that I try to practice my melody line separately. I tried it but my rubato sounds unnatural and vomiting. Have I missed anything?Lillian (Seattle, Washington, USA)
Albert's reply: This is a superb question, and one far too rich to permit a brief reply. Nonetheless, there are some basic principles in the grammar of music that influence rubato.
For those who are unfamiliar with the term, tempo rubato refers to the art of controlling time. The word originates from the Italian rubare, meaning to steal. I once attended a masterclass given by Daniel Barenboim, who cleverly explained the term thus: Tempo rubato means to "steal" time, and since we're ethical people, we give back whatever we steal.
What exactly is it that we "steal" in music? The answer is that we play some notes slightly ahead of time, or slightly late. We can then balance out the phrase by playing the rest of it a bit slower or faster. It's essential to emphasize that tempo rubato is by no means an exact science, and the time taken and given back will almost never truly cancel themselves out—nor should they necessarily. It's simply a guideline, ideal or rule of thumb.
That said, where exactly should we take time? My answer, above all, is dissonances. Dissonances are the notes that are in need of resolution.
The first rule of musical grammar is that, of the seven notes in a scale, some are stable and others are unstable. The most stable note is scale degree 1, the tonic. The other stable notes (in decreasing order of stability) are scale degrees 3 and 5.
Scale degrees 2, 4, 6 and 7 are all unstable.
What's important is the tendency of the unstable notes to resolve to stable ones. Scale degree 2 "wants" to resolve to scale degree 1. I'll use C major as an example:
Similarly, scale degree 4 resolves most often to 3:
Scale degree 6 resolves to 5:
Finally, scale degree 7 resolves upward to 1:
The dissonances—the unstable tones—are the places to take time! This is what makes music emotional.
The next level of dissonance is chromatic tones. These are non-scalar notes (notes not within the scale) that are a half step removed from a scale tone.
I'll provide two examples, both gravitating to scale degree 5 (the dominant). The first is sharp 4 (scale degree 4 raised by a half step):
The other is flat 6 (scale degree 6 lowered by a half step):
If you play these examples on the piano (first establishing the key of C major by playing a C major scale or—better yet—a IV-V-I chord progression), you'll immediately hear that these highly dissonant notes "want" to resolve to the dominant!
These dissonant notes are the prime candidates for tempo rubato. There are other places to apply rubato, depending on the place within the phrase and the overall musical structure, or the rhythm, but this is the best place to start.
I hope this wasn't too technical an explanation, but by now you should recognize that rubato is not simply arbitrary, and that there is indeed a logic behind it!