For a vibrating string, the fundamental frequency represents the first harmonic. Overtones are vibrational modes at higher frequencies, occurring at integer multiples of the fundamental frequency.
- The fundamental frequency is the first harmonic.
- The first overtone is the second harmonic, with a frequency double that of the fundamental.
- The second overtone is the third harmonic, with a frequency triple that of the fundamental.
Consequently, "overtone" specifically denotes the second harmonic.