Who decided how many keys a piano would have?

Answer 1

Many different people have created different versions of the piano, such as the Grand and the Steinway Grand pianos, but almost every modern piano has 36 black keys and 52 white keys for a total of 88 keys (seven octaves plus a minor third cord, from A0 to C8). Although, some pianos, such as Bosendorfer pianos, for example, extend the normal range down into F0, with one other model going as far as C0, making a full eight octave range. These extra keys are sometimes hidden under a small hinged lid than can cover the keys to prevent visual disorientation for pianists unfamiliar with the extra keys. On others, the colors of the extra white keys are reversed (black instead of white). The extra keys are added primarily for the increased resonance for the associated strings; that is, they vibrate sympathetically with other strings whenever the damper pedal is depressed and thus give a fuller tone. Only a very small number of works composed for piano actually uses these notes. More recently, the Stuart and Sons piano company has also manufactured extended-range pianos, with the first 102 key piano. On their instruments, the frequency range extends from C0 to F8, which is the widest practical range for the acoustic piano. The extra keys are the same as other keys in appearance.

Small studio upright acoustical pianos with only 65 keys have been manufactured for use by roving pianists. Known as gigpianos and still containing a cast iron harp, these are comparatively lightweight and can be easily transported to and from engagements by only two people. As their harp and is longer than that of a spinet or console piano, they have a stronger bass sound that to some pianists is well worth the trade-off in range that a reduced key-set offers.

The toy piano manufacturer Schoenhut started manufacturing both grands and uprights with only 44 or 49 keys, and shorter distance between the keyboard and the pedals. These pianos are true pianos with action and strings. The pianos were introduced to their product line in response to numerous requests in favor of it.