Page 112 - Master Handbook of Acoustics

FIGURE 5-8 Harmonic content of the open strings of the violin. The lower-frequency tones sound
richer because of the closely packed harmonics.

Wind Instruments

In many musical instruments, resonance in pipes or tubes can be considered primarily one

dimensional. (Resonances in three-dimensional rooms are discussed in later chapters.) Standing-
wave effects are dominant in pipes. If air is enclosed in a narrow pipe closed at both ends, the
fundamental (twice the length of the pipe) and all its harmonics will be formed. Resonances are
formed in a pipe open at only one end at the frequency at which the pipe length is four times the
wavelength, and results in odd harmonics. Wind instruments form their sounds this way; the length of
the column of air is continuously varied, as in the slide trombone, or in jumps as in the trumpet or

French horn, or by opening or closing holes along its length as in the saxophone, flute, clarinet, and
oboe.
The harmonic content of several wind instruments is compared to that of the violin in the
spectrographs of Fig. 5-9. Each instrument has its characteristic timbre as determined by the number
and strength of its harmonics and by the formant shaping of the train of harmonics by the structural
resonances of the instrument.