Artistic Piano Tuning

Here are the answers to some frequently asked questions.

What is inharmonicity?  All pianos have inharmonicity.  Grands have less.  Spinets have more.  That is one reason we study tuning for years and use equipment such as the SAT III and not $20 guitar tuners.  Guitar type tuning equipment cannot calculate the partials that piano strings actually do vibrate at and only use theoretical frequencies.  If a piano was tuned using a guitar tuner type instrument, it would sound dull, flat, lifeless.

This short article from Wikipedia explains the difference between whole frequency multiples and partials.

In music, inharmonicity is the degree to which the frequencies of overtones (known as partials, partial tones, or harmonics) depart from whole multiples of the fundamental frequency. Acoustically, a note perceived to have a single distinct pitch in fact contains a variety of additional overtones. Many percussion instruments, such as cymbals, tam-tams, and chimes, create complex and inharmonic sounds. In stringed instruments such as the piano, the less elastic the strings are (that is, the shorter, thicker, and stiffer they are), the more inharmonicity they exhibit.

When a string gets thick enough, compared to the length of the string, it stops behaving as a string and starts acting more like a cylinder (a tube of mass), which have different harmonics than strings. On wind instruments, the harmonic overtones are even multiples of the main frequency. However, on stringed instruments the overtones are inharmonic, which is is caused by a "fastening fault in the string endings"; the string endings are fastened at each end, which means that they cannot "vibrate all the way to its ends." As such, the "effective length of a string is shorter than its geometrical length," especially for shorter, stiffer strings.^[1]

In 1943, Schuck and Young were the first scientists to measure the spectral inharmonicity in piano tones. They found that the spectral partials in piano tones are progressively stretched. In 1962, Harvey Fletcher's research indicated that the spectral inharmonicity is important for tones to sound piano-like. They proposed that inharmonicity is responsible for the "warmth" property common to real piano tones. ^[2]. "Inharmonicity is not necessarily unpleasant. Fletcher, Blackham, and Stratton [1] pointed out that a slightly inharmonic spectrum added certain “warmth” into the sound. They found that synthesized piano tones sounded more natural when the partials below middle C were inharmonic."^[3]

Pianos are tuned by ear by technicians called piano tuners who listen for the sound of "beating" when two notes are played together. Piano tuners must deal with the inharmonicity of piano strings, which is present in different amounts in all of the ranges of the instrument, but especially in the bass and high treble registers. Piano strings are under enormous tension compared with the strings on a violin or guitar, and as a result, piano strings are much harder and stiffer. Another factor that can cause problems is the presence of rust on the strings or dirt in the windings. ^[4]These elements can result in inharmonicity, which has the effect of slightly raising in frequency of the higher modes, which means that they cease to be exact integer multiples of the fundamental.

The harmonic series of strings does not fall exactly into whole-number multiples of a fundamental frequency, but rather each harmonic is slightly sharper than a whole-number ratio, and this sharpness increases as higher tones in the harmonic series are reached. This means that an aurally tuned octave will be a "stretched octave" which is slightly wider than the just 2:1 ratio. The amount of stretching depends on the style of piano and is determined mainly by the length of the strings. On a piano, the notes in the higher register will end up being tuned slightly sharper than those in the lower octave. This is less apparent on longer pianos which have proportionally thinner strings, because string inharmonicity is directly related to the ratio of string thickness to length. (for more information, see Piano acoustics).

• Do strings break during tuning?  They can. They can and do break even while playing.  Having a string break is  much more likely to happen with pianos that are old or have not been tuned in a long time. Strings can break just because the elasticity of the steel is gone.  Piano wire is good for about 30 years.  After that it is on its way downhill.  It becomes elongated and loses its liveliness, elasticity, and becomes more prone to breaking.  With exposure to high humidity levels over long periods, strings become rusted and corroded.  At the junction where rusted strings wrap around pins, rust corrosion forms a hardened bond between the two.  Then, during a tuning, when your piano technician turns the pins to stretch the strings, the inflexible, rusted string snaps at this joint.

 Occasionally I run into very very old pianos that have thin plates and pitches more than 100 cents (a semi-tone) flat.  There are several risks in trying to raise pitch on these pianos of strings breaking, bridges cracking or even the plate cracking but these are very rare events.  If the pin block is bad the tuning pin may not allow the pitch change.  I have seen old pianos where pins unwound themselves immediately after being tuned and would not hold a higher pitch. 

                      Fujan Tuning Lever

Can you do repairs?  Yes. Any repairs, even minor, will take additional time and may need to be rescheduled depending on the situation.  I have accounts set up with three major piano parts wholesalers where I can buy any needed strings, keytops or practically any piano part or accessory.  I carry hundreds of piano repair parts on my truck however; repairs are not covered as a part of the normal tuning cost.  I can service Dampp-Chaser Systems. I charge $40 per hour plus parts cost on repair.