Tuesday, August 28, 2012

Musician’s Journal: Free-Drumming and Visual-Motor Space

This is from an email I wrote to Walter Freeman (neuroscientist, UCal Berkeley) and Ralph Holloway (neuroscientist, Columbia U) on April 6, 2002. This is a sequel to an early post on learning to play 3-against-2 but does not depend on it.
Walter and Ralph,

I noticed something interesting the other day that has to do with “free drumming” (to be defined). I seemed to be making choices in visual-motor space rather than auditory space. This is quite different from what I do when improvising on the trumpet, where I seem to make choices in auditory space. That is to say, when playing the trumpet I make choices in terms of what I want to hear rather than in terms of what I want my body to do. I’m not sure whether or not this is because I’m considerably more expert on the trumpet than on my drum.


Let me begin by describing my drum. It’s what’s called a tongue drum or slit drum. It’s a wooden box about 24 inches along its greatest dimension (which is oriented horizontally and transverse when playing) and 8 inches along the other dimensions. It has six “tongues” cut into the top (playing) surface arranged in three rows with two tongues in each row. The tongues are of different lengths but are not precisely tuned. While you can, in most cases, easily hear which tongue in any pair is higher, you cannot assign any particular interval to the pitch difference. I should note, however, that you can get different sounds from any given tongue depending on where you hit it. Thus you can hit a long tongue in such a place that the tone will sound higher than that you get when hitting a shorter tongue. The major point, however, is simply that the tongues are not precisely tuned and, in consequence, you cannot play melodic lines and riffs. This is a drum, not a six-toned marimba.

So, the melodic and harmonic imagination I employ when playing the trumpet isn’t very useful here. Rhythm, of course, remains. But we do need a term for the higher and lower aspect of the sound. Brain imaging data does suggest that interval perception is different from pitch perception and that, in turn, suggests that our ordinary sense of melody is really the joint produce of interval and pitch perception. Thus interval perception by itself tells you whether one tone is more or less higher or lower than another and gives some sense of the magnitude of the difference. But the ordinary sense of melody combines that with perception of the pitches of the individual tones in the melodic stream. My drum patterns are thus based on rhythm, interval, volume and, to a limited extent, timbre.

In most musical situations drums play repetitive patterns. That is certainly the case, for example, with African polyrhythms. Each player has a certain pattern to play and she plays it more or less without variation for the duration of the performance, or performance segment. There may be some variation here and there, but it’s not large and not systematic. In a given performance the master drummer may signal a change, at which time everyone will switch to a new pattern. This doesn’t happen often, and it always happens in prescribed and well-understood ways. The master drummer is the only one who’s free to play something other than a repetitive pattern. Even then, he’s generally not doing the sort of thing a jazz drummer or a tabla player does when they are soloing; the range of variation is generally more restricted.

When I talk of free drumming I mean anything other than playing the same pattern over and over and over without (significant) variation. Free drumming requires that you make a lot of choices. So, how are those choices made?

In general, I haven’t the foggiest idea. But, in the course of working on one set of patterns, I noticed that I seemed to be thinking in visual-motor terms when decided to switch from one pattern to another within the same set. The patterns in this particular set involved six or strokes, alternately right and then left. The stokes were made at isochronous intervals and differed with respect to which tongues were hit. One pattern had all six strokes on one particular tongue, another pattern had one stroke on each of the six tongues, in a particular order. If we assign the tongues numbers, and designate strokes by L (for left) and R (for right) the set of patterns looks like this:

1) stroke: R L R L R L 
  tongue: 1 1 1 1 1 1

2) stroke: R L R L R L 
  tongue: 1 2 2 2 2 2

3) stroke: R L R L R L 
  tongue: 1 2 3 3 3 3

4) stroke: R L R L R L 
  tongue: 1 2 3 4 4 4

5)  stroke: R L R L R L 
  tongue: 1 2 3 4 5 5

6)  stroke: R L R L R L 
  tongue: 1 2 3 4 5 6

This scheme doesn’t tell you about the spatial location of these tongues, and that is an important aspect of execution. Tongues 1, 3, 5 and extend toward the center from the right side of the drum face while tongues 2, 4, and 6 extend in from the left side.

When I say that I seemed to be using a visual-motor space in deciding to switch from one pattern to another. Thus, in deciding to switch from, say, pattern 2 to pattern 3, I thought of it in terms of where my hands were moving. I consciously directed my hands to move in a different way. In this case the decision means that the right hand moves from tongue 2 to tongue 3 in order to execute the third stroke in the pattern and then left hand moves from tongue 2 to tongue 3 in order to execute the fourth stroke in the pattern. Both hands then remain at tongue 3 for the fight and sixth strokes in the pattern (rather than continuing at tongue 2 as in the second pattern).

Once I had noticed that I seemed to be making decisions in visual-motor space I then “tested” that observation by attempting to execute the choice in auditory space. That is, at some point I decided I wanted to hear pattern three rather than pattern two. My hands then changed their movements so that I could hear what I wanted to hear without me having explicitly to direct them.

I then played around a bit and noticed that, in general, it is difficult for me to direct free drumming activity using only auditory space. I can do it as long as the choices are from a limited set of alternatives. But, if I want to be able to range freely through my repertoire of motor patterns for drumming, then I have to make many, probably the majority, of the choices on a visual-motor basis. [I do think my “decision space” is both visual-motor and auditory, but . . . . I'm now straining at the limits of introspection.] I take this to mean that I don’t “hear” these patterns very “exactly.” I think that that, in turn, means that I don’t have a good mapping between the visual-motor execution space and the auditory perception space. So, to move freely I’ve got to make many/most decisions in visual-motor space and hope that the result is pleasing in auditory space.

Often it is, but not always. Obviously I’d like to decrease the occurrence of displeasing sounds, either by preventing them, or by developing strategies for playing a subsequent line that has the effect of converting a “mistake” into an interesting little invention. But that’s a topic I don’t want to go into now.

1 comment:

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