Tempo curves considered harmful
A christmas story with lots of sound examples discussing the state of art in music perception research on musical expression and music technology.
'Reasonable?' he reacted angry, 'it sounds reasonable, yes, but your numerical calculations have nothing to do with the way I played it, whatsoever. The musical structure, my dear friends, remember the musical structure. How often do I have to repeat this. Timing is related to structure!'

[play] The theme from the six variations composed by Ludwig van Beethoven on the duet "Nel cor più non mi sento."

Full paper with sound examples (or pdf version)

Lecture on same topic (1991)

More information.