Musical Notes

Due to the physical principals governing the sound generated by vibrating strings or columns of air in wind instruments, tones of simple instruments consist principally of fundamental frequency and its harmonics, with the perceived pitch normally the fundamental. (The fundamental is often called the first harmonic.) As in many of the examples of Fourier series you’ve seen, it’s common for the fundamental to have the highest power. But this is not necessarily the case for music signals in general. Wind instruments and the human voice in many cases have far greater energy concentrated in upper harmonics than at the fundamental, especially when producing notes near the low end of the instrument’s range. According to A. Woods’ The Physics of Music, a French horn playing at 130 Hz, one octave below middle C, is measured as having 1%, 19%, 21%, 48%, 4%, 5%, and 2% of its energy in the fundamental through 7th harmonics, respectively. A bassoon may have its largest energy as high as the sixth harmonic when it reaches a low note, which is why, although you think you hear a really low pitch coming from the bassoon, somehow it just doesn’t sound nearly as low as if the same note were played on, for example, a pipe organ. Keep these ideas in mind as you spectrally analyze your music.

The pitch corresponding to a particular letter in the range A- doubles each time we move up an octave. Because there are 12 (even-tempered) “half-steps” in an octave, each step up to an adjacent note on the piano represents a logarithmically equivalent increase by a factor 21/12. The notes of a single octave starting at middle C are approximately as follows:

Note Frequency (Hz) C 262 C]/[ 277 D 294 D]/E[ 311 E 330 F 349 F ]/G[ 370 G 392 G]/A[ 415 A 440 A]/B[ 466 B 494 C 523