One of the technical areas of piano tuning is described below. This may be more information than some customers want. However, there are some inquiring minds who love the details.
The Tempered Scale:
The piano "temperament" refers to the intervals between notes on the musical scale. Every pitch can be derived, electronically or aurally, from a relationship with a chosen fixed pitch source. Temperament is a term in a piano tuning. One string per note, of one or two octaves, is set (tuned) to the desired relationship with each other. This establishes the temperament (basis) for tuning the remaining notes on the instrument. When a piano has been tuned using an equal temperament, the octave intervals have been divided into smaller equal steps, each having equal frequency ratios between the adjacent notes. These are the smallest intervals in the tempered scale that is commonly used in modern music. Each of these intervals represent 1/12 the width of the octave and are referred to as a semitone or half-step. In the tempered scale, the frequency between each interval is perceived as being the same distance apart.Before I learned about the tempered scale, I wondered why classical music often lists the key. For example "Piano Concerto in A minor" or "Chopin's Piano Concerto in F minor". Why did these classical composers care what key? The answer lies in the historical temperaments of that era. There are many references to the tempered scale, its history, and examples of the historical temperaments. Importantly, there is no such thing as no temperament (See Temperament Figure 1) in a piano tuning scale. To accommodate the imperfections in the scale, there must be some "imperfections" built into the tuning. The various historical temperaments will cause a composition to sound different depending upon what key it is played in. If played in a modern equal tempered scale, the difference may be undetectable other than the relative pitch reference. But in the original classical temperaments, the difference is notable.You can easily find considerable information on the historical temperaments. If you really like to read the details, you can search on-line for "same song in historical temperaments" and you may find recordings where you can hear the differences. Below is a very simple diagram to show why there must be a temperament for the piano scale. But again, search for more information and you will find enough to keep you reading and listening for a long time.