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Saturday, June 19, 2010

The Subjectivity of an Objective Sound: Is the Length of a Note Definite?

Is the length of a note definite? Yes...and no.

In the video "Physics of Sound: Daniel Barenboim on the Duration of Notes" from PBS's The Music Instinct, the acclaimed conductor and pianist, Daniel Barenboim, speaks to the definite nature of the duration of notes. Unlike the subjective quality of a sound, such as a "beautiful" sound, Barenboim points out that the duration of a sound is objective and definite: "the duration of sound and it’s relation to silence is a very objective thing."

And that got me thinking, is the duration of a sound definite? Why, yes, it seems so simple--a sound has a definite start and end, explained by the laws of physics. So why I am still not convinced? Because as a musician, as a pianist, I believe that my body expression, my hand and arm movements and gestures, may shape a listener's perception of the music. Now the question is, does it?

An article by M. Schutz and M. Kubovy from the University of Virginia, titled "Seeing Music: Do We Hear Silent Gestures?" describes a study that addresses the question: Can gestures change the duration of a musical note? The article includes videos of the gestures and easy-to-understand figures, and is also described in more detail at M. Schutz's website. The experiment is described below:
We recorded a world-renowned percussionist performing notes using long and short gestures on a professional quality marimba (a percussion instrument similar to a xylophone), a sample of which is shown in Figure 1. Participants then rated the duration of each note twice: once with the gesture (audio-visual), and once without (audio-alone). In the audio-visual condition they were instructed to ignore visual information and base their ratings on the sound alone.
Video of 1) A Long Stroke 2) A Short Stroke

As shown in Figure 2, although notes produced by long and short gestures were indistinguishable when presented as audio alone, these same notes were judged to be significantly different when presented with the corresponding gesture. This effect occurred despite instructing participants to ignore visual information when making their ratings. Our results indicate that while gesture fails to alter the sound of the note, it (serendipitously) alters the way the note sounds.

When the subjects were shown a video of the gesture and told to listen to the note (visual and auditory), they rated it correspondingly shorter or longer than when only told to listen to the note (only auditory). Furthermore, a similar study that involved monitoring brain activity of subjects showed that the auditory areas of the brain actually lighted up for correspondingly longer or shorter periods of time with the gesture than without the gesture. This means that in the case of a long gesture, the listeners didn't just think the note sound longer, but actually heard the note as longer.

There's a difference between asking, "Is the duration of a sound definite?", and "Is the duration of a musical note definite?" The answer is yes and no, respectively. The brain aims to understand the world around us, often sacrificing accuracy for understanding, distorting reality in order to process it better. In the case of a pure sound, a sound that isn't processed by a brain, the duration of the sound is definite. But in the case of music, in the case of a musical note that is processed by a brain (for any sound that isn't processed by some listener wouldn't be called music) , the length is subjective. After all, the brain distorts reality, as evidenced by the phenomenon of visual capture--the dominance of visual information over auditory information. In the end, all human experience is subjective, and the question becomes a distinction between laws of nature and laws of human nature.

Is the length of a note definite? Perhaps we should first ask the proverbial question, "If a tree falls in the woods, does it make a sound?"

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