Can musical expression be understood?

In 1985 the composer György Ligeti published some wonderful Etudes for piano. I regularly listen to them ever since. They were also the material (or at least a few bars of “Cordes Vides”) to test an idea for an expression editor: a system that was aimed to facilitate editing operations that are musically meaningful while at the same time amounting to perceptually sound results. The editor, named Expresso, was conceived as a calculus of expression. Quite an ambitious project that aimed to formally describe how different types of expression are linked to different types of musical structure.

The research was inspired by several researchers in the field of “musical expression”: Henry Shaffer, Eric F. Clarke, John Sloboda,Christhoper Longuet-Higgins, Johan Sundberg, Alf Gabrielsson (just to name a few European researchers), all of them contributed, along with quite a few fellow researchers all over the world, to an understanding on how "expressive nuances" in music performance make the difference between one and another performance. A recent paper by Luke Windsor (University of Leeds) summarizes and elaborates on this research. You might like it.

Windsor, W.L. et al. (2006). A structurally guided method for the decomposition of expression in music performance. The Journal of the Acoustical Society of America, 119(2), 1182. DOI: 10.1121/1.2146091

A 2006 recording of Glenn Gould?

Sony Music recently released a new recording (made in 2006) of Glenn Gould performing the Goldberg Variations. Curious, not? The recording was made using measurements of the old recordings and then regenerating the performance on a computer-controlled grand piano, a modern pianola.

This technology dates from the early nineties, a time when several piano companies (including Yamaha and Bösendorfer) combined MIDI and modern solenoid technology with the older idea of a pianola. Old paper piano rolls with recordings of Rachmaninoff, Bartok, Stravinsky and others were translated to MIDI and could be reproduced ‘live’ on modern instruments like the Yamaha Disklavier. Until now, the only left challenge was to be able to do this for recordings of which no piano-rolls were available.

Besides the technicalties of all this, for most people the real surprise —or perhaps disillusion— might well be the realization that a piano performance can be reduced to the ‘when’, ‘what’ and ‘how fast’ the piano keys are pressed. Three numbers per note can fully capture a piano performance, and it allows for replicating any performance on a grand piano(-la). The moment a pianist hits the key with a certain velocity, the hammer releases, and any gesture that is made after that can be considered merely dramatic: it will have no effect on the sound. This realization puts all theories about the magic of touché in a different perspective.

Nevertheless, while it is relatively easy to make the translation from audio (say a recording from Glenn Gould from 1955) to the what (which notes), and the when (timing) in a MIDI-like representation, the problem is in the ‘reverse engineering’ of key velocity. What was the speed of Gould’s finger presses on the specific piano he used? The Zenph Studios claim to have solved it for at least a few recordings. Only trust your ears :-)

Piano touch unraveled?

A few postings ago I mentioned a remake of Glenn Gould’s Goldberg variations. It was related to the topic of piano touch (or touché), a notion pianists and music lovers often talk about, and that is, nevertheless, surrounded with a lot of magic.

Several researchers are researching this topic, including Werner Goebl and Caroline Palmer at McGill University, Canada. They presented their recent findings at the SMPC conference on music perception and cognition in Montreal. Using a movement tracking device it was possible to track a pianist’s finger movements on a digital piano keyboard (Apparently a grand piano could not be used because of the need to film/measure these movements from the piano towards the hands; see photo).

By analyzing the performances of twelve professional pianists, they found that different finger movements did not lead to differences in timing precision or in tone intensity. That is a novel finding. However, the actual relation between the finger movements and the resulting velocity of the piano key after contact was not studied as yet (a replication of this study on a modern pianola —like the Yamaha Disklavier or Bösendorfer— seems a logical next step).

My hunch is that the finger dynamics will not matter so much (as was in part suggested by this study). The gestures made by a pianist, including finger movements and what is generally referred to as piano touch, have more to do with habit and a sense of control, then that they actually have an influence on the key velocity that, next to the timing, effectively contributes to the sound and musical quality of the performance. This type of research will find out soon …