Here are some pieces of technical
information related to piano tuning.
This may include more details than
some customers want to read. However
for those who love the details, see the
information below.
Pitch, Inharmonicity & Tuning:
To fine-tune a piano, first the overall tension must be correct. If it
is not correct, the instrument may need a "pitch-raise" to establish
the correct tension and enable the instrument to hold a tuning at
concert pitch (A440). Once the correct tension is established, the
technician must make very small adjustments to each string to
fine-tune the instrument.
Each piano is somewhat unique due to something called
"inharmonicity". In addition to the full string length, which
represents the fundamental frequency, strings vibrate in a number
of shorter sections separated by "nodes". The nodes separate
additional related frequencies that piano tuners refer to as partials.
Some musicians may refer to these partials as overtones or
harmonics. We won't present an argument here regarding which
term is correct (See Partials figure 2 below diagramming the first 6
partials). However, piano tuners refer to them as partials. These
related frequencies of a tuned piano may not match up exactly
with the mathematically determined harmonic frequencies due to a
number of issues relating to the size, tension, length, materials and
imperfections in the steel strings. (If you want a very short
demonstration of partials/harmonics, ask me during your next tuning.)
The "scale" of the piano, the design that includes string length,
diameter, materials, and tension, also impacts the inharmonicity
and tuning approach. The tuner must deal with the unique
inharmonicity characteristic of each piano. Therefore, the
technician does not simply match the strings to a given set of
pitches. Years ago there were some tuners who carried a set of 12
tuning forks to set the initial middle octave. However, small
changes are needed in each individual piano to adjust for the
inharmonicity that is unique for each acoustic piano. Your tuner
assesses this, via listening to the interaction among notes and
partials. A slight variation is applied from the theoretical standard
to make your piano sound its best.