A440 is the 440 Hz tone that serves as the standard for musical pitch. A440 is the musical note A above middle C (A4). The hertz (symbol: Hz) is the SI unit of frequency. ... Pitch is the perceived fundamental frequency of a sound. ... In Western music, the expression middle C refers to the note C or Do located exactly between the two staves of the grand staff, quoted as C4 in note-octave notation (also known as scientific pitch notation). ... This is a virtual piano with 88 keys tuned to A440, showing the frequencies, in cycles per second (Hz), of each note (i. ...

In 1939, an international conference recommended that the A above middle C be tuned to 440 Hz. This standard was taken up by the International Organization for Standardization in 1955 (and was reaffirmed by them in 1975) as ISO 16. Since then it has served as the audio frequency reference for the calibration of pianos, violins, and other musical instruments. 1939 (MCMXXXIX) was a common year starting on Sunday (link will display full year calendar). ... This article or section does not cite any references or sources. ... 1975 (MCMLXXV) was a common year starting on Wednesday. ... FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ... A short grand piano, with the top up. ... The violin is a bowed string instrument with four strings tuned in perfect fifths. ...

Tuning a piano is an example of a simple frequency calibration that is actually done with the human ear. The piano tuner listens to a standard musical pitch and compares it to the same note on the piano keyboard. The piano is then adjusted (by tightening or loosening strings), until it agrees with the audio standard. Piano tuner Piano tuner redirects here. ... For an alternative meaning, see ear (botany). ...

The smallest frequency offset that a piano tuner can hear depends on many factors, including the sound volume, the duration of the tone, the suddenness of the frequency change, and the musical training of the listener. However, the just noticeable difference is often defined as 5 cents, where 1 cent is 1/100 of the ratio between two adjacent notes on the piano's keyboard, i.e. 1/100 of an equally tempered semitone. In psychophysics, a just noticeable difference, customarily abbreviated with lowercase letters as jnd, is the smallest difference in a specified modality of sensory input that is detectable by a human being or other animal. ... The cent is a logarithmic unit of measure used for musical intervals. ... An equal temperament is a musical temperament -- that is, a system of tuning intended to approximate some form of just intonation -- in which an interval, usually the octave, is divided into a series of equal steps (equal frequency ratios). ... A semitone (also known in the USA as a half step) is a musical interval. ...

In the movie Phantasm, The Tall Man has a weakness to this frequency. This article is being considered for deletion in accordance with Wikipedias deletion policy. ...

Image File history File links Sine_wave_440. ... Software development stages In computer programming, development stage terminology expresses how the development of a piece of software has progressed and how much further development it may require. ... In trigonometry, an ideal sine wave is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C, where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C...

See also

• Concert pitch