music and latency (Robert Port )

Subject: music and latency
From:    Robert Port  <port(at)CS.INDIANA.EDU>
Date:    Fri, 13 Sep 2002 11:46:25 -0500

The problem of adapting to delays in motor control is surely nothing unique to musicians and generally requires little or no practice to achieve. Ordinary people can do this with ease. Try tapping a pen on the desk with your left hand and simultaneously slap a very flexible ruler on the desk with the other. Of course, if you move your wrists simultaneously, the ruler will slap later than the pen. It takes only about 2 strokes for your right hand to phase shift so that the two sounds are simultaneous. It works just as well if someone else is making the series of taps (instead of your left hand). Or better yet, alternate the left and right hands. Many tools create this latency problem but as long as there is a salient auditory consequence of the motion, people will adjust the gesture timing to put the auditory effect where they want it. Of course, when the phase shift is large - eg, greater than a half a cycle -- it becomes much more difficult to do. I did an unpublished experiment on this some years ago using a metronome and a computer key that had controllable delays before producing a beep. Nonmusician subjects found the task (to produce beeps simultaneous with the metronome) very easy until the delay was large relative to the metronome period. Bob Port ( ( ( O ) ) ) ( ( ( O ) ) ) ( ( ( O ) ) ) Lingstcs/Comp Sci/Cogntv Sci ROBERT F. PORT 330 Memorial Hall, Indiana University Bloomington, Indiana 47405 812-855-9217 Fx 812-855-5363

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