# Audio frequency > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Audio_frequency > Markdown URL: https://mediated.wiki/source/Audio_frequency.md > Source: https://en.wikipedia.org/wiki/Audio_frequency > Source revision: 1300483771 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{short description|Sound whose frequency is audible to the average human}} {{Sound measurements}} An '''audio frequency''' or '''audible frequency''' ('''AF''') is a [periodic](/source/periodic_function) [vibration](/source/vibration) whose [frequency](/source/frequency) is [audible to the average human](/source/human_hearing_range). The [SI unit](/source/SI_unit) of frequency is the [hertz](/source/hertz) (Hz). It is the property of [sound](/source/sound) that most determines [pitch](/source/Pitch_(music)).{{Cite book|last1= Pilhofer |first1=Michael |title=Music Theory for Dummies|url=https://books.google.com/books?id=CxcviUw4KX8C|year=2007|publisher=For Dummies|page=97|isbn=9780470167946 }} The generally accepted standard [hearing range](/source/hearing_range) for humans is 20 to 20,000 Hz (20 kHz).{{cite web|title=Hyperphysics|url=http://hyperphysics.phy-astr.gsu.edu/hbase/sound/earsens.html|access-date=19 September 2014}}{{cite journal|last1=Heffner|first1=Henry|last2=Heffner|first2=Rickye|title=Hearing Ranges of Laboratory Animals|journal= Journal of the American Association for Laboratory Animal Science|date=January 2007|volume=46|issue=1|pages=20–2|pmid=17203911|url=http://www.ingentaconnect.com/content/aalas/jaalas/2007/00000046/00000001/art00003|access-date=19 September 2014}}{{cite book|last=Rosen|first=Stuart|title=Signals and Systems for Speech and Hearing|date=2011|publisher=BRILL|page=163|edition=2nd|quote=For auditory signals and human listeners, the accepted range is 20Hz to 20kHz, the limits of human hearing}} In air at [atmospheric pressure](/source/atmospheric_pressure), these represent sound waves with [wavelength](/source/wavelength)s of {{convert|17|m|feet}} to {{convert|1.7|cm|inch}}. Frequencies below 20 Hz are generally felt rather than heard, assuming the [amplitude](/source/amplitude) of the vibration is great enough. Sound waves that have frequencies below 20 Hz are called [infrasonic](/source/infrasonic) and those above 20 kHz are called [ultrasonic](/source/ultrasonic). Sound propagates as mechanical vibration waves of pressure and displacement, in air or other substances.{{cite web |title=Definition of SOUND |url=http://www.merriam-webster.com/dictionary/sound |access-date=3 October 2016}} In general, frequency components of a sound determine its "color", its [timbre](/source/timbre). When speaking about the frequency (in singular) of a sound, it means the property that most determines its [pitch](/source/Pitch_(music)).{{Cite book |last1=Pilhofer |first1=Michael |url=https://books.google.com/books?id=CxcviUw4KX8C |title=Music Theory for Dummies |publisher=For Dummies |year=2007 |isbn=978-0-470-16794-6 |page=97}} Higher pitches have higher frequency, and lower pitches have lower frequency. The frequencies an ear can hear are limited to a [specific range of frequencies](/source/Threshold_of_hearing). The [audible frequency](/source/audible_frequency) range for humans is typically given as being between about 20 Hz and 20,000 Hz (20 kHz), though the high frequency limit usually reduces with age. Other [species](/source/species) have different hearing ranges. For example, some dog breeds can perceive vibrations up to 60,000 Hz (60 kHz).{{cite web |last=Condon |first=Tim |year=2003 |editor-last=Elert |editor-first=Glenn |title=Frequency range of dog hearing |url=https://hypertextbook.com/facts/2003/TimCondon.shtml |accessdate=2008-10-22 |website=The Physics Factbook}} In many media, such as air, the [speed of sound](/source/speed_of_sound) is approximately independent of frequency, so the wavelength of the sound waves (distance between repetitions) is approximately inversely proportional to frequency. ==Frequencies and descriptions== {| class="wikitable" ! Frequency (Hz) ! [Octave](/source/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](/source/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](/source/Labial_consonant) and [fricative](/source/fricative) sounds lie. |- | 8,192 to 16,384 | 10th | Brilliance, the sounds of bells and the ringing of cymbals and [sibilance](/source/sibilance) in speech. |- | 16,384 to 32,768 | 11th | Beyond brilliance, nebulous sounds approaching and just passing the upper human threshold of hearing |} [[File:Middle C, or 262 hertz, on a virtual oscilloscope.png|thumb|[Oscillogram](/source/Oscilloscope) of a [pure tone](/source/pure_tone) [middle C](/source/C_(musical_note)) (262 Hz). (Scale: 1 square is equal to 1 [millisecond](/source/millisecond))]] thumb|C5, an octave above middle C. The frequency is twice that of middle C (523 Hz). thumb|C3, an octave below middle C. The frequency is half that of middle C (131 Hz). {| class="wikitable" ! MIDI note ! Frequency (Hz) ! Description ! Sound file |- | 0 | 8.17578125 | Lowest [organ](/source/Organ_(music)) note | n/a ([fundamental frequency](/source/fundamental_frequency) inaudible) |- | 12 | 16.3515625 | Lowest note for tuba, large pipe organs, [Bösendorfer](/source/B%C3%B6sendorfer) Imperial grand piano | n/a ([fundamental frequency](/source/fundamental_frequency) inaudible under average conditions) |- | 24 | 32.703125 | Lowest C on a standard 88-key [piano](/source/piano) | File:Audio Frequency tone, C1, 32.70hz.ogg |- | 36 | 65.40625 | Lowest note for [cello](/source/cello) | File:Audio frequency tone, C2, 65.41hz.ogg |- | 48 | 130.8125 | Lowest note for [viola](/source/viola), [mandola](/source/mandola) | File:Audio frequency tone, C3, 130.81hz.ogg |- | 60 | 261.625 | [Middle C](/source/Middle_C) | File:Audio Frequency tone, Middle C, C4, 261.63hz.ogg |- | 72 | 523.25 | C in middle of [treble clef](/source/treble_clef) | File:Audio Frequency tone, C5, 523.25hz.ogg |- | 84 | 1,046.5 | Approximately the highest note reproducible by the average female [human voice](/source/human_voice) | File:Audio Frequency tone, C6, 1046.50hz.ogg |- | 96 | 2,093 | Highest note for a [flute](/source/flute) | File:Audio Frequency tone, C7, 2093hz.ogg |- | 108 | 4,186 | Highest note on a standard 88-key piano | File:Audio frequency tone, C8, 4186hz.ogg |- | 120 | 8,372 | | File:Audio frequency tone, C9, 8372hz.ogg |- | 132 | 16,744 | Approximately the tone that a typical [CRT television](/source/CRT_television) emits while running. | File:Audio frequency tone, C10, 16744hz.ogg |} ==See also== *[Absolute threshold of hearing](/source/Absolute_threshold_of_hearing) *[Hypersonic effect](/source/Hypersonic_effect), controversial claim for human perception above 20,000 Hz *[Loudspeaker](/source/Loudspeaker) *[Musical acoustics](/source/Musical_acoustics) *[Piano key frequencies](/source/Piano_key_frequencies) *[Scientific pitch notation](/source/Scientific_pitch_notation) *[Whistle register](/source/Whistle_register) ==References== {{Reflist}} {{Authority control}} Category:Acoustics Category:Sound Category:Sound measurements Category:Physical quantities Category:Audio engineering --- Adapted from the Wikipedia article [Audio frequency](https://en.wikipedia.org/wiki/Audio_frequency) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Audio_frequency?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.