Keyboard expression often shortened to expression is the ability of the keyboard of a
keyboard instrumentto respond to the dynamics of the music.
For example, the
pianoresponds exceptionally well to the force with which the keys are initially pressed; it is velocity sensitive. Several of its predecessors, such as the harpsichord, were less velocity sensitive than the piano, which is one of the key advantages of the piano.
clavichordand some electronic keyboards also respond to the force with which a key is held down after the initial impact; they are pressure sensitive. This can be used by a skilled clavichord player to slightly correct the intonation of the notes when playing on a clavichord, and/or to play with a form of vibratoknown as bebung.
There is some confusion relating to the term "pressure sensitive", with some using it as a
synonymfor "velocity sensitive". To avoid this confusion, pressure sensitivity is sometimes called aftertouch.
Both velocity and (true) pressure sensitivity are supported independently by the
In general, only the top of the line electronic keyboards implement true pressure sensitivity, while most (not all) recent electronic keyboards support velocity sensitivity. This has led to an unfortunate tendency for manufacturers and distributors of some inferior keyboards to describe their purely velocity sensitive instruments as "pressure sensitive".
A third form of sensitivity is displacement sensitivity. Displacement sensitive keyboards are often found on organs. Most mechanical organs, and some electrically actuated organs, are displacement sensitive, i.e. you can press a key part way down, and the corresponding note (pipe, reed, or the like) in the organ will produce some lesser amount of sound than when the key is fully depressed. Small tabletop organs and accordions often respond similarly, with sound output increasing as keys are pressed further down. Even the small circular accompaniment ("one button chord") keys found on accordions and on some organs exhibit this phenomenon. Accordingly, some electrically actuated organs have retained this form of keyboard expression:
Other more sophisticated forms of sensitivity are common in organ keyboards. For example, both the Pratt Reed and Kimber Allen 61-key (5-octave) keyboards have provision for installing up to nine rails, so that they can sense various amounts of displacement, as well as velocity in various regimes of distance from the top to the bottom of the key travel of each key.
Some modern instruments such as the Continuum, a midi controller for keyboards, have extremely sophisticated human interface schemes, allowing dynamic control in three dimensions.
It should be noted that, in principle, displacement can be differentiated to get velocity, but the converse is not entirely practical, without some amount of baseline drift. Thus a displacement sensing keyboard may have greater versatility when it is desired to have both organ and piano behaviour in an input device.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Pedal keyboard — The 30 note pedalboard of a Rieger organ. A pedalboard (also called a pedal keyboard, pedal clavier, or, with electronic instruments, a bass pedalboard) is a keyboard played with the feet that is usually used to produce the low pitched bass… … Wikipedia
Microsoft Natural keyboard — Pro, circa Q4 1999. The Microsoft Natural Keyboard is a computer keyboard that was introduced by Microsoft in 1994. The keyboard was a split keyboard with each half of the keyboard separated and tilted upwards and down from the center of the… … Wikipedia
Table of keyboard shortcuts — In computing, a keyboard shortcut is a sequence or combination of keystrokes on a computer keyboard which invokes commands in software. Some keyboard shortcuts require the user to press a single key or a sequence of keys one after the other.… … Wikipedia
Microsoft Expression Studio — Microsoft Expression Developer(s) Microsoft Stable release 4.0 / June 7, 2010; 16 months ago ( … Wikipedia
MIDI keyboard — A close up of one style of MIDI keyboard based on the piano user interface A MIDI keyboard is typically a piano style user interface keyboard device used for sending (MIDI) signals or commands over a USB or MIDI cable to other devices connected… … Wikipedia
Works for keyboard by J.S. Bach — The keyboard works of the German composer Johann Sebastian Bach, originally written for organ, clavichord, and harpsichord, are among the most important and well known of his compositions. Widely varied and ranging over the entire span of his… … Wikipedia
In an Expression of the Inexpressible — Infobox Album Name = In an Expression of the Inexpressible Type = studio Artist = Blonde Redhead Released = start date|1998|9|8 Recorded = Genre = Rock Length = 42:55 (US) 50:38 (JP) Label = Touch and Go Catalog# = TG196CD Producer = Guy… … Wikipedia
Kurzweil K250 — The Kurzweil K250 a.k.a. Kurzweil 250 , K250 or K 250 , manufactured by Kurzweil Music Systems was the first combined live performance and studio electronic musical instrument which produced sound derived from sampled sounds (see:Sampler (musical … Wikipedia
Aftertouch — En musique, l Aftertouch (qui peut être traduit par sensibilité d expression d un clavier) est la capacité d un instrument à répondre à la dynamique du jeu du musicien. Il y a parfois confusion autour du terme d aftertouch, qui est souvent… … Wikipédia en Français
Pressure sensitive — may refer to:* Pressure sensitive adhesive * Pressure sensitive tape * Pressure pad * Piezoelectric sensor * the force with which a key is held after initial impact (see keyboard expression) … Wikipedia