Audio frequency

An audio frequency or audible frequency (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.^[1]

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
v t e

The generally accepted standard hearing range for humans is 20 to 20,000 Hz.^[2][3][4] In air at atmospheric pressure, these represent sound waves with wavelengths of 17 metres (56 ft) to 1.7 centimetres (0.67 in). Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. High frequencies are the first to be affected by hearing loss due to age or prolonged exposure to very loud noises.^{[5][failed verification]}

Frequencies and descriptionsEdit

Frequency (Hz)	Octave	Description
16 to 32	1st	The lower human threshold of hearing, 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.
512 to 2,048	6th to 7th	Defines human speech intelligibility, gives a horn-like or tinny quality to sound.
2,048 to 8,192	8th to 9th	Gives presence to speech, where labial and fricative sounds lie.
8,192 to 16,384	10th	Brilliance, the sounds of bells and the ringing of cymbals and sibilance in speech.
16,384 to 32,768	11th	Beyond brilliance, nebulous sounds approaching and just passing the upper human threshold of hearing

MIDI note	Frequency (Hz)	Description	Sound file
0	8.17578125	Lowest organ note	n/a (fundamental frequency inaudible)
12	16.3515625	Lowest note for tuba, large pipe organs, Bösendorfer Imperial grand piano	n/a (fundamental frequency inaudible under average conditions)
24	32.703125	Lowest C on a standard 88-key piano.
36	65.40625	Lowest note for cello
48	130.8125	Lowest note for viola, mandola
60	261.625	Middle C
72	523.25	C in middle of treble clef
84	1,046.5	Approximately the highest note reproducible by the average female human voice.
96	2,093	Highest note for a flute.
108	4,186	Highest note on a standard 88-key piano.
120	8,372
132	16,744	Approximately the tone that a typical CRT television emits while running.

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.