A pure tone is the sound of only one
frequency, such as that given by a tuning fork or electronic signal generator.
The fundamental note has the greatest
amplitude and is heard predominantly because it has a larger intensity. The other
frequencies such as 2fo, 3fo,
4fo, ............. are called overtones or harmonics
and they determine the quality of the sound.
Loudness is a
physiological sensation. It depends mainly on sound pressure but also on the spectrum of
the harmonics and the physical duration.