Opening toneholes raises pitch by marking where the tube effectively ends

Evidence

By drilling a hole in the side of the tube, we can clearly control the impedance change all the way from negligible change for a very tiny hole, to a dramatic lowering for large one. The tube continues past the hole, where the impedance recovers its value before the hole was encountered. The impedance change causes partial reflection of pressure waves. Large holes will essentially mark the end of the tube (see figure 16.33). Clearly, such a hole will have the effect of raising the pitch, especially of modes with antinodes at the hole position. Clarinet players know that if toneholes are opened in the upper segment of the instrument, the lower segment of the clarinet may be removed—that is, the instrument disassembled—with little consequence (figure 16.34). — Eric J. Heller, Why You Hear What You Hear- An…, 1594

Categorization

• DEFINE: Clarifies the causal mechanism by which toneholes alter effective tube length and pitch.