Sound frequency is the number of cycles of a sound wave per second. The unit of measurement is hertz (Hz) and the frequency of the sound increases as the number of cycles per second increases. Vibrations between 20 and 20,000 cycles per second are considered to be the sound of a person in normal health. Treble sounds are those made by a flute or a bird's song. And the bass sounds are those made by distant distant thunderstorms or guitar sounds.
