Musical keyboard

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This article is about keyboards on musical instruments. For instruments referred to as "keyboards", see Keyboard instrument.
The layout of a typical musical keyboard
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The layout of a typical musical keyboard

A musical keyboard is the set of adjacent depressible levers on a musical instrument which cause the instrument to produce sounds.

Keyboards almost all share the common layout shown. Musical instruments with keyboards of this type include the piano, harpsichord, clavichord, organ, electric piano, electronic piano, digital piano, synthesizer, "arranger keyboard" or "home keyboard" (also called "electronic keyboard"), celesta, dulcitone, accordion, melodica, glasschord, and carillon. Since the most commonly encountered keyboard instrument is the piano, the keyboard layout is often called the piano keyboard.

In spite of their apparent similarity, keyboard instruments of different types often require subtly different techniques. For instance, a piano will produce a louder note the faster the key is depressed. On the other hand the volume and timbre of the sound on the pipe organ are dictated by the flow of air from the bellows and the stops selected by the player; in the harpsichord the strings are plucked and the volume of the note is not perceptibly varied by using a different touch on the keyboard. Players of these instruments must use other techniques to colour the sound. The arranger keyboard uses pre-set drum rhythms which respond to chords played in the left hand by the instrumentalist, with other buttons and switches used to change rhythms and even the voice of the instrument.

The twelve notes of the Western musical scale are laid out with the lowest note on the left; the larger keys (for the seven "natural" notes of the C major scale: C, D, E, F, G, A, B) jut forward. Technically these keys are called Naturals. Because these keys are often coloured white on a keyboard, these are often called the white notes or white keys. The keys for the remaining five notes which are not part of the C major scale (namely C♯/D♭, D♯/E♭, F♯/G♭, G♯/A♭, A♯/B♭) are set back. The correct term for these keys is Accidentals or more often Sharps, or Flats. Because these keys are often coloured black, these notes are often called the black notes or black keys. The pattern repeats at the interval of an octave.

The arrangement of longer keys for C major with intervening, shorter keys for the intermediate semitones dates to the 15th century. Many keyboard instruments dating from before the nineteenth century have a keyboard with the colours of the keys reversed - darker coloured keys for the white notes and white keys for the black notes. A few electric and electronic instruments have had this feature; Vox's electronic organs of the 1960s, Hohner's Clavinet L, one version of Korg's Poly-800 synthesizer and Roland's digital harpsichords. Some 1960s electronic organs used reverse colors or gray sharps or naturals to indicate the lower part(s) of a split keyboard. Farfisa's FAST series of portable organs had black, light gray and dark gray naturals and white sharps. It should be noted that the reverse-colored keys on Hammond organs such as the B3, C3 and A100 are not playable keys; they physically latch when pressed, and serve as selector switches for preset sounds.

A Roland EXR-3 Arranger Keyboard
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A Roland EXR-3 Arranger Keyboard

The chromatic compass of keyboard instruments has tended to increase. Harpsichords often extended over five octaves in the 18th century, while most pianos manufactured since about 1870 have 88 keys. Some modern pianos have even more notes (a Bösendorfer 225 has 92 and a Bösendorfer 290 "Imperial" has 97 keys). Modern synthesizer keyboards commonly have either 61, 76 or 88 keys. Organs normally have 61 keys per manual, though some spinet models have 44 or 49. An organ pedalboard, a keyboard played by the organist's feet, may vary in size from 12 to 32 notes.

Piano keyboard which shows the alignment of the white and the black keys.
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Piano keyboard which shows the alignment of the white and the black keys.

In a typical keyboard layout, "accidental" keys have uniform width, and "natural" keys have uniform width and uniform spacing at the front of the keyboard. In the regions between accidental keys, the width of natural keys C, D and E differ slightly from the width of keys F, G, A and B. This allows close to uniform spacing of 12 keys per octave while maintaining uniformity of 7 natural keys per octave. This scheme has the most uniform distribution, given fixed accidental key width, though not all keyboards are produced this way.

Over the last three hundred years, the octave span distance found on historical keyboard instruments (organs, virginals, clavichords, harpsichords, and pianos) has ranged from as little as 125mm to as much as 170mm. Modern piano keyboards ordinarily have an octave span of 164-165mm, but several reduced-size standards have been proposed and marketed, including a 15/16 size (152 mm octave span) and the 7/8 DS Standard (140 mm octave span) developed by Canadian composer, conductor and pianist Christopher Donison in the 1970s then further developed and now marketed by Steinbuhler & Company, located in Titusville, Pennsylvania. U.S. pianist Hannah Reiman has promoted piano keyboards with narrower octave spans and has a U.S. patent (#6,020,549) on apparatus and methods for modifying existing pianos to provide interchangeable keyboards of different sizes.

There have been variations in the design of the keyboard to address technical and musical issues. For instance, during the sixteenth century, when instruments were often tuned in meantone temperament, some harpsichords were constructed with the G♯ and E♭ keys split into two. One portion of the G♯ key operated a string tuned to G♯ and the other operated a string tuned to A♭, similarly one portion of the E♭ key operated a string tuned to E♭, the other portion operating a string tuned to D♯. This extended the flexibility of the harpsichord, enabling composers to write keyboard music calling for harmonies containing the so-called wolf fifth G-sharp♭ to E-flat♯, but without producing discomfort in the listeners. Other examples of variations in keyboard design include the Janko keyboard and the chromatic keyboard systems on the accordion and bandoneón.

Other instruments share the keyboard layout, although they are not keyboard instruments. For example the xylophone, marimba, vibraphone and glockenspiel all have a separate sounding tone bar for each note, and these bars are laid out in the same configuration as a common keyboard.

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