Preserving Human Expression

The more precise the machine, the less human it sounds; keep breaths, rubato and small errors on purpose.

Related

RubatoVibratoDynamics

The problem

Quantising, tuning and aligning each remove deviation. Once the deviations are gone, the beat is exact and the pitch is exact, and the result sounds like a demonstration file. Human feel is not mysterious. It consists of identifiable deviations that can be removed and can also be put back deliberately.

How it works

Expression comes from three places. Time: rubato borrowing and repaying, melody arriving slightly ahead of or behind the accompaniment. Dynamics: not loudness but changes of touch and breath, so the same note played twice is never identical. Noise: breaths, finger noise, bow noise, pedal, sounds that never appear in the score yet tell a listener a person is playing. A machine defaults to the average, and the average flattens all three at once, very evenly.

Practice

Do not quantise everything; leave ten to twenty milliseconds of deviation. Fade the ends of long notes instead of cutting them. Keep a breath at every phrase, obvious in wind playing and still necessary in strings. Record a passage three times with different weight and timing, then assemble from the best moments rather than keeping the most accurate take. Rubato must pay back what it borrows, so a rush is recovered later. Add roughly five percent timing and velocity variation to generated parts by hand, and avoid repeating the same seed. Finally, compare the played version and the fully automatic one side by side. The difference is what you are trying to keep.

What to listen for

In Chopin's nocturne, listen to tempo flexing with the phrase rather than dividing evenly. In the live Ballade No. 1, listen to timing choices made in the moment. In Du bist die Ruh, listen to where the breaths fall. In the Sarabande of Bach's cello suite, listen to bow speed and the resonance after the note. Human feel lives in places the score does not notate.

Sources

• 演奏表情与量化损失的讨论，依演奏通识与制作实践核对，未抄原文
• Expression, rubato and quantisation loss, checked against general performance practice, no text copied

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