Final answer:
The frequencies above the lowest sound are called harmonics; the lowest sound is the fundamental, and the higher frequencies are overtones. The fundamental is the first harmonic, with subsequent overtones corresponding to higher harmonics.
Step-by-step explanation:
The frequencies that sound above (and with) the lowest sound are called harmonics. In air columns, the lowest-frequency resonance is termed the fundamental, and all higher resonant frequencies are referred to as overtones. The harmonics encompass the fundamental and its overtones with the fundamental being the first harmonic, the first overtone the second harmonic, and so on. These terms are essential when discussing the sources of musical sound and the perception of hearing.