Editing Musical keyboard (section)

==Size and historical variation==
[[File:Syntagma musicum025.gif|thumb|left|Keyboards of [[Halberstadt organ|Nicholas Faber's organ]] for [[Halberstadt]], built in 1361 and enlarged 1495. The illustration is from [[Michael Praetorius|Praetorius]]' ''[[Syntagma Musicum]]'' (1619). At the top is the earliest example of the "seven plus five" layout. The bottom two illustrate the earlier "eight plus four" arrangement]]

The chromatic range (also called ''[[wikt:compass|compass]]'') of keyboard instruments has tended to increase. Harpsichords often extended over five octaves (>60&nbsp;keys) in the 18th century, while most pianos manufactured since about 1870 have 88 keys. The lowest pitch (frequency: 27.5&nbsp;Hz) of an 88-key piano is equivalent to a sub contrabass in the range name. Some modern pianos have even more notes (a [[Bösendorfer]] 290 "Imperial" has 97 keys, and a [[Stuart & Sons]] model has 108 keys<ref>
{{cite news
|url= http://www.abc.net.au/news/2018-09-15/worlds-first-108-key-concert-grand-piano-built-by-australian/10246340
|access-date= 2018-09-15
|title= World's first 108-key concert grand piano built by Australia's only piano maker
|first= Rosie
|last= King
|date= September 14, 2018
|journal= ABC
}}</ref>). While modern synthesizer keyboards commonly have either 61, 76 or 88 keys, small MIDI controllers are available with 25 keys (digital systems allow shifting octaves, pitch, and "splitting" ranges dynamically, which, in some cases, reduce the need for dedicated keys. However, smaller keyboards will typically limit which musical scores can be played). Organs normally have 61 keys per manual, though some spinet models have 44 or 49. An organ [[Pedal keyboard|pedalboard]] is a keyboard with long pedals played by the organist's feet. Pedalboards vary in size from 12 to 32 notes or 42 on a touring organ used by Cameron Carpenter.

In a typical keyboard layout, ''black note'' keys have uniform width, and ''white note'' keys have uniform width and uniform spacing at the front of the keyboard. In the larger gaps between the ''black'' keys, the width of the natural notes 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 seven "natural" keys per octave.

Over the last three hundred years, the octave span distance found on historical keyboard instruments (organs, [[virginals]], [[clavichord]]s, [[harpsichord]]s, and [[piano]]s) has ranged from as little as {{convert|125|mm|in|abbr=on}} to as much as {{convert|170|mm|in|abbr=on}}.
{{Citation needed|date=November 2023}}
Modern piano keyboards ordinarily have an octave span of {{convert|164–165|mm|in|2|abbr=on}}, resulting in the width of black keys averaging {{convert|13.7|mm|in|2|abbr=on}} and white keys about {{convert|23.5|mm|in|2|abbr=on}} at the base, disregarding space between keys. 

In recent years, there has been evidence of a correlation between pianists with smaller hand spans and hand or arm injuries.<ref>{{Cite journal |last1=Kaufman-Cohen |first1=Yael |last2=Portnoy |first2=Sigal |last3=Sopher |first3=Ran |last4=Mashiach |first4=Lital |last5=Baruch-Halaf |first5=Lilach |last6=Ratzon |first6=Navah Z. |date=2018-12-19 |title=The correlation between upper extremity musculoskeletal symptoms and joint kinematics, playing habits and hand span during playing among piano students |journal=PLOS ONE |language=en |volume=13 |issue=12 |pages=e0208788 |doi=10.1371/journal.pone.0208788 |issn=1932-6203 |pmc=6300245 |pmid=30566535|doi-access=free |bibcode=2018PLoSO..1308788K }}</ref><ref>{{Cite journal |last1=Lai |first1=Kuan-Yin |last2=Wu |first2=Shyi-Kuen |last3=Jou |first3=I-Ming |last4=Hsu |first4=Hsiao-Man |last5=Chen Sea |first5=Mei-Jin |last6=Kuo |first6=Li-Chieh |date=2015-11-01 |title=Effects of hand span size and right-left hand side on the piano playing performances: Exploration of the potential risk factors with regard to piano-related musculoskeletal disorders |url=https://www.sciencedirect.com/science/article/pii/S0169814115300299 |journal=International Journal of Industrial Ergonomics |language=en |volume=50 |pages=97–104 |doi=10.1016/j.ergon.2015.09.011 |issn=0169-8141|url-access=subscription }}</ref> Several reduced-size standards have been proposed for these pianists. A 7/8 size ({{convert|140|mm|in|abbr=on}} octave span) keyboard was developed by Canadian Christopher Donison in the 1970s. This size, along with the 15/16 size ({{convert|152|mm|in|abbr=on}} octave span) and a smaller size (130&nbsp;mm (5.1&nbsp;in) octave span) have since been developed and marketed by Steinbuhler & Company in Pennsylvania. These three sizes are registered as DS6.0, DS5.5 and DS5.1. The company was converted to the non-profit [http://dsstandardfoundation.org DS Standard Foundation] in 2018. Hailun USA manufactures pianos in the two alternative DS6.0 and DS5.5 sizes through an agreement with the DS Standard Foundation. Since 2013, a global network of pianists, teachers and performing arts health professionals has been increasingly advocating for change to the 'one size fits all' approach to piano keyboard manufacturing by major companies. This network is known as PASK ([http://paskpiano.org Pianists for Alternatively Sized Keyboards]).<ref>{{Cite web |title=Hailun Pianos |url=https://www.hailun-pianos.com/my-size-keys |access-date=16 November 2022}}</ref> U.S. pianist [[Hannah Reimann]] has promoted piano keyboards with narrower octave spans and has a U.S. patent on the apparatus and methods for modifying existing pianos to provide interchangeable keyboards of different sizes.<ref>Reimann, Hannah. [http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/PTO/srchnum.htm&r=1&f=G&l=50&s1=6,020,549.PN.&OS=PN/6,020,549&RS=PN/6,020,549 Patent claim #6,020,549], August 10, 1998.</ref> Narrower keyboards are available from Steinway & Sons USA in new grand pianos or as a retrofit to existing pianos.<ref>{{Cite web|title=PASK Piano|url=http://paskpiano.org/manufacturers-technicians/|access-date=27 August 2021}}</ref>

There have been variations in the design of the keyboard to address technical and musical issues. The earliest designs of keyboards were based heavily on the notes used in [[Gregorian chant]] (the seven diatonic notes plus B-flat) and as such would often include B{{music|b}} and B{{music|natural}} both as diatonic "white notes", with the B{{music|natural}} at the leftmost side of the keyboard and the B{{music|b}} at the rightmost. Thus, an octave would have ''eight'' "white keys" and only four "black keys". The emphasis on these eight notes would continue for a few centuries after the "seven and five" system was adopted, in the form of the [[short octave]]: the eight aforementioned notes were arranged at the leftmost side of the keyboard, compressed in the keys between E and C (at the time, accidentals that low were very uncommon and thus not needed). During the sixteenth century, when instruments were often tuned in [[meantone temperament]], some harpsichords were constructed with the G{{Music|#}} and E{{Music|b}} keys split into two. One portion of the G{{Music|#}} key operated a string tuned to G{{Music|#}} and the other operated a string tuned to A{{Music|b}}, similarly one portion of the E{{Music|b}} key operated a string tuned to E{{Music|b}}, the other portion operating a string tuned to D{{Music|#}}. This type of keyboard layout, known as the [[enharmonic keyboard]], extended the flexibility of the harpsichord, enabling composers to write keyboard music calling for harmonies containing the so-called ''[[Wolf interval|wolf]]'' fifth (G-sharp to E-flat), but without producing aural discomfort in the listeners (see [[Split sharp]]). The "broken octave", a variation of the aforementioned short octave, similarly used split keys to add accidentals left out of the short octave. Other examples of variations in keyboard design include the [[Jankó keyboard]] and the chromatic keyboard systems on the [[chromatic button accordion]] and [[bandoneón]].

{| class="wikitable sortable"
|+ '''Historical Keyboard Instruments – Extended Comparison'''
! Instrument
! Date of Creation
! City/Country of Origin
! Manuals
! Keys
! Keyboard Position
|-
| [[Clavichord]]
| c. 1400s
| [[Germany]] (possibly [[Flanders]])
| 1
| 36–61
| Center
|-
| [[Virginals|Virginal]]
| c. 1500s
| [[Italy]], [[England]], [[Flanders]]
| 1
| 45–54
| Left of center
|-
| [[Muselar]]
| c. 1500s
| [[Flanders]] (Low Countries)
| 1
| 45–54
| Right of center
|-
| [[Harpsichord]]
| c. late 1500s
| [[Italy]] (developed across Europe)
| 1–2
| 49–61
| Center
|-
| [[Piano]]
| 1700
| [[Florence, Italy]]
| 1
| 85–88
| Center
|}

===Electronic keyboards===
[[File:Korg Monologue Synthesizer.jpg|thumb|The [[Korg Monologue]] synthesizer has 25 slim keys and an E-E range.]]

Simpler electronic keyboards have switches under each key. Depressing a key connects a circuit, which triggers tone generation. Most keyboards use a [[keyboard matrix (music)|keyboard matrix circuit]], in which 8 rows and 8 columns of wires cross — thus, 16 wires can provide 8 × 8 = 64 crossings, which the keyboard controller scans to determine which key was pressed.<ref>Dave Dribin. [http://www.dribin.org/dave/keyboard/one_html/ "Keyboard Matrix Help"], (June 24, 2000).</ref> The problem with this system is that it provides only a crude binary on/off signal for each key. Better electronic keyboards employ two sets of slightly offset switches for each key. By determining the timing between the activation of the first and second switches, the velocity of a key press can be determined, greatly improving the performance dynamic of a keyboard. The best electronic keyboards have dedicated circuits for each key, providing polyphonic aftertouch.

Advanced electronic keyboards may provide hundreds of key touch levels<ref name="fp80">[http://www.rolandus.com/products/details/1276/specs/ Digital piano specs] (100 pressure levels specified).</ref> and have 88 keys, as most pianos do.