fundamental tone

…acoustics, tone sounding above the fundamental tone when a string or air column vibrates as a whole, producing the fundamental, or first harmonic. If it vibrates in sections, it produces overtones, or harmonics. The listener normally hears the fundamental pitch clearly; with concentration, overtones may be heard.

…lowest frequency is called the fundamental; the others, overtones. The frequencies of the overtones may be whole multiples (e.g., 2, 3, 4, etc., of the fundamental frequency, in which case they are called the second, third, fourth, etc., harmonics of the fundamental tone, itself known as the first harmonic). A…