A temperament is a musical system that determines the difference in frequency between any two notes. Invented in the 1500s, the equal temperament divides an octave into twelve semitones that are equally spaced. This allows the pianist to play in any key with a minimum number of flaws in intonation. Most modern pianos are tuned using the equal temperament system. However, there is a growing acceptance of other systems that produce different intonation patterns in the various key signatures. In other words, the notes are not necessarily evenly spaced which means that one key signature can sound distinct from others.
Composers have worked with different temperament systems and, it can be argued, selected key signatures based on the tonal color created by alternate tunings. Tuning a modern instrument to one of these unequal temperaments will not harm the piano and, some would argue, can allow musicians and audiences to experience the emotion of a piece in a more intense and authentic way. At Campbell Piano Shop, we have several temperaments available or we can help you design your own custom system. For a more in-depth history and discussion of temperaments, visit http://unequaltemperament.com