Sometimes
the piano keyboard seems a bit arbitrary. For instance, why are the keys black
and white – and why are there 88 keys?
The
white keys represent the “natural” octave, and the black keys indicate the half
tones within the octave to constitute the Western scale. As for the color, the
easy answer is that keys were originally made with ivory (white) and ebony
(black). Centuries ago, the harpsichord keyboard had the opposite color scheme:
CDE… were black and the half tones were white. Since there are fewer half tones, the result
was that the keyboard was largely black, and it was sometimes harder to see the
line between the keys. With the current white arrangement, the key edges are easier
to see, so the player doesn’t have to pay as much attention to striking the
right key.
Even
the width of the keys have varied over the years; an octave could span as
little as 4.9 inches to as much as 6.7 inches. The standard now is 6.7 inches,
but some smaller sizes have been created and sold in recent years. You can
imagine, though, getter used to one span width and then having to adjust to a different
width; that change could really challenge your muscle memory when performing.
The
number of keys also has an historical back story. The same harpsichord
mentioned above had about 60 keys, but piano composers wanted to broaden the
range of notes to approach other musical instruments such as woodwinds. Seven
octaves seems to be a good range because notes that are even higher can be hard
for some people to hear, and very low
notes can be hard to distinguish between each other. That would result in 85
keys, which was common in the 19th century. The Steinway pianos of
the late 19th century added three lower keys to create more resonance—and
set themselves apart from their competitors;
the 88 keys ended up setting the standard for the industry, which has
been followed ever since. However, 97-key pianos are also sold (again, to
produce a more resonant sound because of the lower strings), and in 2018, a
nine-octave piano (108 key) was built more as an experiment. It should also be
noted that digital pianos sometime have 76, which makes them more portable.
Each of these features impacts the composition
and performance of the piano; each has an evidence-based purpose. So piano
keyboards are not arbitrary after all.
