Natural Science Forum / Physics / Acoustics / October 2005

Here are some techniques you can use to create special effects from
pianos.  You will need a piano, and a microphone input to your computer
music mixing software.  A Yamaha Disklavier or similar would also be
useful, but is not essential.

On a normal piano, the maximum repeat rate of an individual note is
about ten per second, but if a piano note could be repeated at the rate
of about 25 notes per second, the result would be a single continuous
tone.  You can check this out yourself:  play the same note repeatedly
at a rate of 6 or 7 notes per second, record the result and then speed
it up by four times.  The output is a continuous tone two octaves
higher than the original note, and depending on how you varied the
loudness while repeating the note, the resulting continuous tone will
also vary in loudness.  Try it out on the melody near the start of
'Ondine' from Ravel's 'Gaspard de la Nuit', for example.

Notes tuned one sixth-tone apart or less produce a smooth pitch-bend
when played consecutively.  If you tune some of the piano strings to
adjacent sixth-tones and apply the same technique as above (play notes
at the rate of 6 or 7 per second and then speed up the result four
times), you can imitate the glissando slides that a violin or voice can
produce.

Using a combination of the above techniques, complex sound sculptures
can be constructed.  Non-piano sounds, such as human speech, can be
quantised using a spectrum analyser, to give a frequency distribution
for each 25th of a second.  The notes equivalent to the spectrum
analysis output can be played on the piano (at quarter-speed two
octaves lower than the intended final pitch, and then speeded up four
times) to produce a 'talking piano'.  To achieve the best effect
(remembering that the undamped strings of an acoustic piano can
resonate along with the notes being played), you will need to decide
how the piano should be tuned, and precisely how to reorganise the
initial spectrum analyser output into short continuous tones and
pitch-bends - the whole process is rather time-consuming and involves a
lot of trial and error experimentation, but can result in musically
interesting sounds that have never before been heard.