Audio frequency

Sound measurements
Characteristic	Symbols
Sound pressure	p, SPL, LPA
Particle velocity	v, SVL
Particle displacement	δ
Sound intensity	I, SIL
Sound power	P, SWL, LWA
Sound energy	W
Sound energy density	w
Sound exposure	E, SEL
Acoustic impedance	Z
Audio frequency	AF
Transmission loss	TL

An audio frequency (abbreviation: AF) or audible frequency is characterized as a periodic vibration whose frequency is audible to the average human. It is the property of sound that most determines pitch and is measured in hertz (Hz).

The generally accepted standard range of audible frequencies is 20 to 20,000 Hz, although the range of frequencies individuals hear is greatly influenced by environmental factors. Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. Frequencies above 20,000 Hz can sometimes be sensed by young people. High frequencies are the first to be affected by hearing loss due to age and/or prolonged exposure to very loud noises.

Frequencies and descriptions

Frequency (Hz)	Octave	Description
16 to 32	1st	The human threshold of feeling, and the lowest pedal notes of a pipe organ.
32 to 512	2nd to 5th	Rhythm frequencies, where the lower and upper bass notes lie.
1024 to 2048	6th to 7th	Defines human speech intelligibility, gives a horn-like or tinny quality to sound.
4096 to 8192	8th to 9th	Gives presence to speech, where labial and fricative sounds lie.
16384 to 32768	10th	Brilliance, the sounds of bells and the ringing of cymbals. In speech, the sound of the letter "S" (8000–11000 Hz)

MIDI Note	Frequency (Hz)	Description	Sound File
C-2	4.09	Lowest note for Gregg Bailey's 128' PVC Subcontrabass clarinet	N/A (inaudible)
C-1	8.18	Lowest organ note	N/A (inaudible)
C0	16.35	Lowest note for tuba, large pipe organs, Bösendorfer Imperial Grand Piano
C1	32.70	Lowest C on a standard 88-key piano.
C2	65.41	Lowest note for cello
C3	130.81	Lowest note for viola, mandola
C4	261.63	Middle C
C5	523.25	Lowest note for a piccolo.
C6	1046.50	Approximately the highest note reproducible by the average female human voice.
C7	2093	Highest note for a flute.
C8	4186	Highest note on a standard 88-key piano.
C9	8372
C10	16744	Approximately the tone that a typical CRT television emits while running.

See also

• Loudspeaker
• Piano key frequencies