What differentiates piano tuning and pitch raise/lowering?
According to WordReference.com, tuning is defined by “to adjust [a musical instrument] to a correct or given standard of pitch” but also “the state of being in harmony” [with other instruments]. Of course, this also applies to piano tuning!
Another source describes pitch raise/lowering as “raise (or lowering) all the strings to their proper average tension levels, and only then can the piano be accurately tuned.”
Piano tuners must adjust pitch -or intonation- with a tuning hammer by manipulating tuning pins following a specific procedure that both allows the most stable tuning as possible and preserves the instrument’s integrity. They must do so by dividing the octave into 12 equal semitones while taking into account the piano’s inharmonicity. For this purpose, piano tuners regularly use softwares applications like Tunelab and Verituner. Also, some performers – mostly for early music – will at times require an unequal division of the 12 semitones. This is called unequal temperament and will be the topic in an upcoming article.
Above all, what’s the most important for a perfect tuning is the purity of unisons and octaves. Approximately two-thirds of the piano keys are related to three strings that should be tuned in unison.
If you play a single note on the piano and hear some quick wave effects, this means the unison is out of tune. If you wait until the piano sounds dissonant before asking for a piano maintenance, your technician might have to pitch raise or lower the instrument prior to doing an actual tuning. Such a significant adjustment will be avoided by tuning the piano twice a year, allowing a more rigorous maintenance of the instrument and its condition by the technician.
Pitch raise or lowering
Pitch naturally oscillates as humidity level varies. During summer, the soundboard will swell until it affects the strings angle on the bridge and consequently, pitch goes up.
During winter, pitch goes down as the soundboard shrinks and lowers the tension of the strings.
Pianos are designed and calibrated to sustain their middle A at 440 Hz. With this standard pitch, pianos can be played in harmony with other instruments. This explains why a piano should be kept as close as possible to the correct pitch. When the piano moves too far away from it, such as a quarter tone or more, your technician will have to work harder to bring back your piano on pitch and will probably charge you additional fees.
Moreover, as your piano moves further from pitch before every tuning, its tuning stability will be increasingly reduced.