This story was originally covered by PRI's Here and Now. For more, listen to the audio above.
As a cognitive neuroscientist with a specialty in music perception and cognition, Daniel Levitin wanted to know how pianists could convey (or fail to convey) emotion through their performances. He called this emotional communication through music "expressivity." He explains:
The interesting thing about the mechanics of the piano -- that is, the physics of the instrument -- is that unlike the voice or the violin, where you can change the pitch, you can have glissandos and swooping in and out of notes, when you hit a C, it plays exactly C. You can't play it slightly sharp or slightly flat, and really, the only control the pianist has is how hard to hit the note, when to press the key, when to release it, and where to put the peddle.
To study how pianists express emotions in their performances, Levitin brought in professional pianist Tom Plaunt and had him play Chopin's Nocturne Op.32 No.1 as he would for a concert. He played the piece on the Yamaha Disklavier, a specialized piano that records every detail of how each note is played.
The key to Plaunt's expressivity is what Levitin calls his "deviation from perfect metronomic performance." He explains, "Of course, what professional pianists do is they add expression by deviating from the regular. They don't play every 8th note exactly the same length. They play some longer and some shorter, and some louder and some softer." Put another way, "The ear is drawn to change -- the brain is a giant change detector."
To prove this, the neuroscientist used a computer to manipulate the original recording and create different levels of variation from robotically precise to extreme deviations. He asked listeners, both musicians and laypeople, to rate the versions from zero to one hundred in emotional quality. People consistently identified the original as the most expressive, and were able to correctly identify Levitin's dulled-down variations by accurate degrees, and responded negatively to the amplified deviation.
People could hear the difference, and they didn't particularly like the 125 [percent deviation]. They didn't feel more expression or more emotion in it, in fact, it sort of gets to a point where it's too much, and people think there's something funny going on.
When asked why very subtle differences in a performance can have such a large effect on an audience, Levitin replies:
It's useful to think of music as a form of emotional communication. And we all know from relationships that we're in, that when you're trying to explain something that's important to you and that's meaningful, if you don't get the words right and you don't get the timing and the cadence right, the message is really misunderstood. It's the same with musical notes. It's up to the musician to interpret those notes in a way that is meaningful and convincing. One wrong note, or one note that's overplayed, and you feel manipulated, perhaps.
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