Acoustic Terms and Definitions: Frequency or audio frequency (AF)
Frequency or audio frequency (or AF) is a periodic vibration whose frequency is in the band audible to the average human, the human hearing range. The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch.
Humans can hear and spans from 20 Hz to 20,000 Hz. The audio spectrum range spans from 20 Hz to 20,000 Hz and can be effectively broken down into seven different frequency bands, with each band having a different impact on the total sound.