When considering a time-related signal in terms of frequency, it shows a more or less large number of harmonics in addition to the fundamental.
icsare integer multiples of the fundamental. Thus the first harmonic, which is also the second harmonic
, has twice thefrequency of
the fundamental, the second harmonic has three times the frequency of the fundamental, etc. The first harmonic of concert pitch "A" with a frequency of 440 Hz has 880 Hz, the second 1.360 kHz, the third 1.760 kHz, etc. The fundamental, together with the harmonics, characterizes the sound.