Keyboard expression

Last updated

Keyboard expression is the ability of a keyboard musical instrument to change tone or other qualities of the sound in response to velocity, pressure or other variations in how the performer depresses the keys of the musical keyboard. Expression types include:

Contents

Keyboard instruments offer a range of expression types. Acoustic pianos, such as upright and grand pianos, are velocity-sensitive—the faster the key strike, the harder the hammer hits the strings. Baroque-style clavichords and professional synthesizers are aftertouch-sensitive—applied force on the key after the initial strike produces effects such as vibrato or swells in volume. Tracker pipe organs and some electronic organs are displacement-sensitive—partly depressing a key produces a quieter tone.

Velocity sensitivity

The piano is an example of a velocity-sensitive keyboard instrument Fortepiansteinway.JPG
The piano is an example of a velocity-sensitive keyboard instrument

The piano, being velocity-sensitive, responds to the speed of the key-press in how fast the hammers strike the strings, which in turn changes the tone and volume of the sound. Several piano predecessors, such as the harpsichord, were not velocity-sensitive like the piano. Some confuse pressure-sensitive with velocity-sensitive. To avoid this confusion, pressure sensitivity is often called aftertouch. The MIDI standard supports both velocity and aftertouch.

In general, only high-end electronic keyboards implement true pressure sensitivity, while most professional-quality electronic keyboards support velocity sensitivity. Cheaper electronic keyboards, such as toy electronic keyboards and basic learning keyboards manufactured by Casio and Yamaha in the US$100 price range, do not have velocity sensitivity, but instead a manually-adjusted note volume.

Pressure sensitivity or aftertouch

A modern reproduction of a Baroque-era clavichord Hillclavichord.jpg
A modern reproduction of a Baroque-era clavichord

The clavichord and some electronic keyboards also respond to the amount of force applied after 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 vibrato known as bebung. Unlike in a piano action, the tangent does not rebound from the string; rather, it stays in contact with the string as long as the key is held, acting as both the nut and as the initiator of sound. The volume of the note can be changed by striking harder or softer, and the pitch can also be affected by varying the force of the tangent against the string. When the key is released, the tangent loses contact with the string and the vibration of the string is silenced by strips of damping cloth.

By applying a rocking pressure up and down the key with the finger, a performer can slightly alter the vibrating length of the string itself, producing a vibrato quality known as bebung . While the vibrato on fretless string instruments such as the violin typically oscillates in pitch both above and below the root note, clavichord bebung only produces pitches above the note. Sheet music does not often explicitly indicate bebung. Composers generally let players apply bebung at their discretion. When sheet music does indicate bebung, it appears as a series of dots above or below a note; the number of dots indicates the number of finger movements.

A 2000s-era digital keyboard Yamaha DGX-205.jpg
A 2000s-era digital keyboard

On electronic keyboards and synthesizers, pressure sensitivity is usually called aftertouch. The vast majority of such instruments use only channel aftertouch: that is, one level of pressure is reported across the entire keyboard, which affects either all notes pressed (even ones not being pushed into aftertouch) or a subset of the active notes in some instruments that allow this level of control. A minority of instruments have polyphonic aftertouch, in which each individual note has its own sensor for pressure that enables differing usage of aftertouch for different notes.

Aftertouch sensors detect whether the musician is continuing to exert pressure after the initial strike of the key. The aftertouch feature allows keyboard players to change the tone or sound of a note after it is struck, the way that singers, wind players, or bowed instrument players can do. On some keyboards, sounds or synth voices have a preset pressure sensitivity effect, such as a swell in volume (mimicking a popular idiomatic style of vocal performance with melodies) or the addition of vibrato.

On some keyboards - a good example of such an instrument being Yamaha's programmable synthesiser-workstation, the Yamaha EX5 [1] [2] [3] - the player can select the effects to which aftertouch applies. This allows a performer to custom-tailor the effect that they desire. It may also facilitate the imitation of various non-keyboard instruments. For example, a keyboardist who wishes to imitate the sound of a heavy metal guitar solo could use a distortion guitar sound, and then set the aftertouch feature to apply a pitch bend to the note.

Displacement sensitivity

A tracker pipe organ uses a mechanical action; as such, when the keys are only partly depressed, the volume and tone are changed. Opus127.jpg
A tracker pipe organ uses a mechanical action; as such, when the keys are only partly depressed, the volume and tone are changed.

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., when a key is partially pressed, the corresponding note (pipe, reed, etc.) in the organ produces a different, quieter sound than when the key is fully pressed. In some organs, the pitch or tone frequency may also be altered. 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 expressiona 34-rank organ in the Swiss village of Ursy is equipped with hi-tech features from Syncordia, including what some erroneously claim is the first non-mechanical action that directly controls the opening of a pipe organ's pallets in direct proportion to key movement, ostensibly combining the virtues of electric action with the intimate control of tracker action. However, Vincent Willis' 1884 patent Floating Lever pneumatic action also had this capability. [4]

Other more sophisticated sensitivity forms are common in organ keyboards. Both the Pratt Reed and Kimber Allen 61-key (5-octave) keyboards have provision for up to nine rails so 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 that provide dynamic control in three dimensions. 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 be better at providing both organ and piano feel in a single keyboаrd controller.

Most digital pianos implement a displacement-sensitive keyboard, in order to simulate the sound-stopping length of the note after the key is released. On an acoustic piano, releasing a key after being partially depressed will result in a quieter, shorter sound stopping. The displacement-sensitive keyboard on a digital piano were designed to simulate the similar effect.

Other types

Acoustic pianos have expression pedals that change the response or tone of the instrument.

On small upright pianos, the soft pedal (also called una corda or half-blow pedal) moves the hammers closer to the strings. On grand pianos, the soft pedal moves the hammers sideways so each hammer strikes only part of its string group.

The sustain pedal (also called damper pedal) prevents individual key dampers from lifting when the player releases the key. All notes played with the sustain pedal ring until the player releases the sustain pedal (or until the note completely decays). With the dampers not applied, octave, fifth, and other overtones vibrate sympathetically, producing a richer sound. Most electronic keyboards also have a sustain pedal that holds notes and chords, but only high-end digital keyboards reproduce the sympathetic vibration effect.

Electromechanical keyboards and electronic keyboards offer a range of other expression devices. Electromechanical keyboards such as the Hammond organ offer additional means of keyboard expression by modifying the starting, stopping, or speed of the rotating Leslie speaker or by engaging a variety of vibrato or chorus effects. Digital "clones" of Hammond organs offer recreations of these effects, along with other effects. The VK-9 digital organ, for example, offers a proximity-sensitive detector that triggers the Leslie speaker, a ring modulator, or other effects.

Some effect pedals used with electromechanical keyboards such as the Fender Rhodes electric piano or digital keyboards respond to loudness and so, indirectly, to key velocity. Examples include overdrive pedals, which produce a clean sound for softer notes, and a distortion effect for louder notes—and fixed wah-wah pedals that filter the audio signal based on loudness.

Related Research Articles

<span class="mw-page-title-main">Clavichord</span> Musical instrument

The clavichord is a stringed rectangular keyboard instrument that was used largely in the Late Middle Ages, through the Renaissance, Baroque and Classical eras. Historically, it was mostly used as a practice instrument and as an aid to composition, not being loud enough for larger performances. The clavichord produces sound by striking brass or iron strings with small metal blades called tangents. Vibrations are transmitted through the bridge(s) to the soundboard.

<span class="mw-page-title-main">Musical keyboard</span> Musical instrument component

A musical keyboard is the set of adjacent depressible levers or keys on a musical instrument. Keyboards typically contain keys for playing the twelve notes of the Western musical scale, with a combination of larger, longer keys and smaller, shorter keys that repeats at the interval of an octave. Pressing a key on the keyboard makes the instrument produce sounds—either by mechanically striking a string or tine, plucking a string (harpsichord), causing air to flow through a pipe organ, striking a bell (carillon), or, on electric and electronic keyboards, completing a circuit. Since the most commonly encountered keyboard instrument is the piano, the keyboard layout is often referred to as the piano keyboard.

<span class="mw-page-title-main">Piano</span> Keyboard instrument

The piano is a keyboard instrument that produces sound when pressed on the keys. Most modern pianos have a row of 88 black and white keys: 52 white keys for the notes of the C major scale and 36 shorter black keys raised above the white keys and set further back, for sharps and flats. This means that the piano can play 88 different pitches, spanning a range of a bit over seven octaves. The black keys are for the "accidentals", which are needed to play in all twelve keys.

<span class="mw-page-title-main">Digital piano</span> Musical instrument

A digital piano is a type of electronic keyboard instrument designed to serve primarily as an alternative to the traditional acoustic piano, both in how it feels to play and in the sound it produces. Digital pianos use either synthesized emulation or recorded samples of an acoustic piano, which are played through one of more internal loudspeakers. They also incorporate weighted keys, which recreate the feel of an acoustic piano. Some digital pianos are designed to also look like an upright or grand piano. Others may be very simple, without a stand.

<span class="mw-page-title-main">Electric piano</span> Electro-mechanical keyboard musical instrument

An electric piano is a musical instrument which produces sounds when a performer presses the keys of a piano-style musical keyboard. Pressing keys causes mechanical hammers to strike metal strings, metal reeds or wire tines, leading to vibrations which are converted into electrical signals by pickups which are then connected to an instrument amplifier and loudspeaker to make a sound loud enough for the performer and audience to hear. Unlike a synthesizer, the electric piano is not an electronic instrument. Instead, it is an electro-mechanical instrument. Some early electric pianos used lengths of wire to produce the tone, like a traditional piano. Smaller electric pianos used short slivers of steel to produce the tone. The earliest electric pianos were invented in the late 1920s; the 1929 Neo-Bechstein electric grand piano was among the first. Probably the earliest stringless model was Lloyd Loar's Vivi-Tone Clavier. A few other noteworthy producers of electric pianos include Baldwin Piano and Organ Company and the Wurlitzer Company.

<span class="mw-page-title-main">Electronic keyboard</span> Musical instrument

An electronic keyboard, portable keyboard, or digital keyboard is an electronic musical instrument, an electronic derivative of keyboard instruments. Electronic keyboards include synthesizers, digital pianos, stage pianos, electronic organs and digital audio workstations. In technical terms, an electronic keyboard is a synthesizer with a low-wattage power amplifier and small loudspeakers.

Keytar is a keyboard instrument similar to a synthesizer or MIDI controller that is supported by a strap around the neck and shoulders, similar to the way a guitar is held.

<span class="mw-page-title-main">Pedal keyboard</span> Musical keyboard played with the feet, usually used for low-pitched notes

A pedalboard is a keyboard played with the feet that is usually used to produce the low-pitched bass line of a piece of music. A pedalboard has long, narrow lever-style keys laid out in the same semitone scalar pattern as a manual keyboard, with longer keys for C, D, E, F, G, A and B, and shorter, raised keys for C, D, F, G and A. Training in pedal technique is part of standard organ pedagogy in church music and art music.

<span class="mw-page-title-main">Expression pedal</span>

An expression pedal is an important control found on many musical instruments including organs, electronic keyboards, and pedal steel guitar. The musician uses the pedal to control different aspects of the sound, commonly volume. Separate expression pedals can often be added to a guitar amplifier or effects unit and used to control many different aspects of the tone.

<span class="mw-page-title-main">Stage piano</span> Electronic musical instrument

A stage piano is an electronic musical instrument designed for use in live performances on stage or in a studio, as well as for music recording in jazz and popular music. While stage pianos share some of the same features as digital pianos designed for home use and synthesizers, they have a number of features which set them apart. Stage pianos usually provide a smaller number of sounds, with these being of higher quality than the ones found on regular digital pianos and home synthesizers.

<span class="mw-page-title-main">MIDI keyboard</span> Piano-style keyboard that sends MIDI inputs to a computer or device

A MIDI keyboard or controller keyboard is typically a piano-style electronic musical keyboard, often with other buttons, wheels and sliders, used for sending MIDI signals or commands over a USB or MIDI 5-pin cable to other musical devices or computers. MIDI keyboards lacking an onboard sound module cannot produce sounds themselves, however some models of MIDI keyboards contain both a MIDI controller and sound module, allowing them to operate independently. When used as a MIDI controller, MIDI information on keys or buttons the performer has pressed is sent to a receiving device capable of creating sound through modeling synthesis, sample playback, or an analog hardware instrument. The receiving device could be:

<span class="mw-page-title-main">Korg DW-8000</span> Hybrid digital-analog synthesizer

The Korg DW-8000 synthesizer is an eight-voice polyphonic hybrid digital-analog synthesizer 61-note keyboard instrument released in 1985. By the time of its launch, Korg had already begun a common trend in 1980s synthesizer design: using numerical codes to access or change parameters with its predecessor - the Korg Poly-61, which was widely regarded as the company's first "knobless" synthesizer. This was a move away from the heavily laden, complex control panels of earlier designs.

Polyphony is a property of musical instruments that means that they can play multiple independent melody lines simultaneously. Instruments featuring polyphony are said to be polyphonic. Instruments that are not capable of polyphony are monophonic or paraphonic.

Finger vibrato is vibrato produced on a string instrument by cyclic hand movements. Despite the name, normally the entire hand moves, and sometimes the entire upper arm. It can also refer to vibrato on some woodwind instruments, achieved by lowering one or more fingers over one of the uncovered holes in a trill-like manner. This flattens the note periodically creating the vibrato.

<span class="mw-page-title-main">Multivox</span>

Multivox was an American-based synthesizer company since the mid-1970s until the 1980s. Originally it was founded in the mid-1940s as the guitar and amplifier manufacturing subsidiary of Peter Sorkin Music Company, a New York-based retailer/wholesaler. Then eventually it established separate corporate identity, and after the close of Sorkin Music in the mid-1970s, it continued in existence for fourteen years, according to the Blue Book of Guitar Values. In addition to synthesizers, the company marketed several effects pedals. These included the Big Jam series guitar effects line.

<span class="mw-page-title-main">Yamaha DX21</span> 1985 digital FM synthesizer

The Yamaha DX21 is a digital controlled bi-timbral programmable digital FM synthesizer with a four operator synth voice generator which was released in 1985. It uses sine wave-based frequency modulation (FM) synthesis. It has two FM tone generators and a 32-voice random-access memory (RAM), 32 user voices and 128 read-only memory (ROM) factory preset sounds. As a programmable synth, it enables users to create their own unique synthesized tones and sound effects by using the algorithms and oscillators. The instrument weighs 8 kg (17.6 lbs). On its release, it sold for $795.

The history of home keyboards lies in mechanical musical instrument keyboards, electrified keyboards and 1960s and 1970s synthesizer technologies.

<span class="mw-page-title-main">ROLI Seaboard</span> Electronic musical keyboard by ROLI

The Seaboard is a musical keyboard-style MIDI controller manufactured by the British music technology company ROLI. It has a continuous sensor-embedded flexible rubber surface for playing the keys instead of traditional lever-style "moving keys". Some models, like the RISE Seaboard Grand, have an onboard sound engine. It has what the manufacturer calls "5D technology" which consists of five types of responsiveness to player actions: "strike", "glide" and "press", front to rear movement "slide" sensitivity, and release–velocity "lift". These responsiveness tools can be used to play the Seaboard with microtonal pitch bend sounds, by moving the finger from note to note, or trigger a vibrato effect into a string patch just by wiggling the finger, which would not be possible on a traditional MIDI controller using only the keys. The Seaboard also features polyphonic aftertouch, and a built-in USB- charged battery. There are three Seaboard models: the small minikey BLOCK, the RISE, and the GRAND, an 88-key keyboard with an onboard sound engine.

<span class="mw-page-title-main">Digital accordion</span>

A digital accordion is an electronic musical instrument that uses the control features of a traditional accordion to trigger a digital sound module that produces synthesized or digitally sampled accordion sounds or, in most instruments, a range of non-accordion sounds, such as orchestral instruments, pipe organ, piano, guitar, and so on. Digital accordions typically encode and transmit key presses and other input as Musical Instrument Digital Interface (MIDI) messages. Most digital accordions need to be plugged into a keyboard amplifier or PA system to hear their sounds.

The Nautilus is a music workstation manufactured by Korg, a successor to Kronos 2, which comes with Kronos' nine different synthesizer sound engines and other similar features. It was announced in November 2020 with availability in January 2021.

References

  1. "Yamaha - product page EX5".
  2. "Sound on Sound: EX5".
  3. "Vintage Synths - EX5".
  4. Douglas E. Bush/Richard Kassel: The Organ., 2006, S. 631-633