JAVS Spring 2022

change in speed so that these effects ne gate each other, and the loudness remains the same, which brings us to the next ap plication. Exercise 3: Still playing long notes halfway between the bridge and the fingerboard, alternately decrease the weight of the bow while in creasing its speed, and increase the weight while decreasing the speed, keeping the sound’s loudness unchanged (Figure 8). All the effects discussed thus far are expressed in the equation of the First Law.

Figure 4: small triangle, small sound (slow, heavy bow).

Figure 5: big triangle, big sound (a light, fast bow).

Now for some exercises you can experiment with on your own instrument to make these ideas clearer.

Though the two triangles in Figure 8 have the same area, you can plainly see that they look different in the sound chart, implying that there’s something different about those sounds, which you can easily verify by ear. For that matter, there’s more about the sound that changed in Exercises 1 and 2 than just its loudness. How can we describe this other aspect of the sound, and how is it displayed by a sound chart?

Exercise 1: Play long notes with the bow halfway between the bridge and the end of the fingerboard. While playing, keep the bow weight the same, but change the speed of the bow, listening for how the sound gets louder as the bow moves faster, and softer as the bow moves slower (Figure 6). You may find that you need to resist the urge to lighten the bow when slowing it down. Exercise 2: Play the same long notes, but instead of changing the speed, change the bow weight, listening for how the sound gets louder when the bow gets heavier, and softer when lighter (Figure 7). The change in loudness is re flected in the difference between the areas of the triangles in the sound charts.

Figure 8: the area of the two triangles, and therefore the loudness of the two sounds, is the same.

The Second Law: D

The Second Law of Sound Production deals with the density of the sound, which is represented by D and determined by the relative balance between the bow weight and speed, rather than their com bined product. To the ear, density is the concentration of the sound—how thick, rich, or tightly-packed it seems. The op posite of a dense sound can be described as thin or airy.

Figure 6: changing the bow speed to change the loudness of the sound.

Figure 7: changing the bow weight to change the loudness of the sound.

Since both the weight and speed of the bow can be con trolled to change the sound’s loudness, it is possible to move the loudness in one direction with a change in weight while moving it in the opposite direction with a

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Journal of the American Viola Society / Vol. 38, No. 1, Spring 2022