fréquence harmonique de la fréquence de modulation

11:40 Nov 23, 2023 

For better understanding:
The fundamental frequency is also called the 1st harmonic; the other harmonics are known as higher harmonics. As all harmonics are periodic at the fundamental frequency, the sum of harmonics is also periodic at that frequency. The set of harmonics forms a harmonic series.
:
The nodes of a vibrating string are harmonics.
:
Harmonics may also be called "overtones", "partials" or "upper partials". The difference between "harmonic" and "overtone" is that the term "harmonic" includes all of the notes in a series, including the fundamental frequency (e.g., the open string of a guitar) while the term "overtone" only includes the pitches above the fundamental.
https://en.wikipedia.org/wiki/Harmonic

The best way to compare the harmonics is with a string in which both the fundamental and the higher octaves, e.g. c', c'', c''', resonate.
These can be analysed by Fourier analysis

See:
Fourier transform of bass guitar time signal of open string A note (55 Hz).
https://en.wikipedia.org/wiki/Fourier_analysis

As a graduate in electrical engineering, I also had to study Fourier analysis.