I had expected the taps to be approximately correct, but jittered either
side of the correct points by a roughly normal distribution. However,
this is not what I observe.
Take a look at the first attachment. There's an obvious U-shapred trend
in the error graph, and I have no idea why. It appears very, very
frequently though. But aside from that, the errors look much more like a
random walk than a normal distrubition. The timing error in each tap
appears to be highly correlated with its neighbors.
The second attachment shows a similar pattern (although the U-shapred
trend is now inverted). Note the difference in tempo between the two
examples.
I hypothesize that what actually happens is that my tapping is actually
running off an internal mental clock, which is being adjusted by a
feedback loop that keeps it reasonably in-phase with the actual
drumbeat. Hence the random-walk variations.
Of course, it's possible that the music I'm tapping to actually contains
subtle tempo variations. Or that some of these patterns are prediction
errors. I think what I need to do is perform a tapping experiment with a
timing source of known tempo, so I can get genuine error measurements.
(Currently it's tricky to reperate human tapping errors from computer
prediction errors.)
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Attachments:
Download 'bpm1.png' (14 KB)
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Preview of image 'bpm1.png'
![bpm1.png](/povray.off-topic/attachment/%3C4c0f6a79%40news.povray.org%3E/bpm1.png?preview=1)
Preview of image 'bpm2.png'
![bpm2.png](/povray.off-topic/attachment/%3C4c0f6a79%40news.povray.org%3E/bpm2.png?preview=1)
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