In our well-tempered musical culture, all musical keys tend to sound the same, except for being higher or lower. Yet throughout the eighteenth and nineteenth centuries, composers enjoyed the rich and expressive variety in the way different keys sounded. Rousseau described D major as being suited for “gaiety or brilliance,” Schumann spoke of C major as “simple, unadorned, while Schubert, describing Bb minor, said “preparation for suicide sounds in this key.” The San Francisco Symphony has a wonderful demonstration of how different keys have different qualities when played on a piano as it would have been tuned in Beethoven’s day.
When you listen to the difference in tone quality and color between the keys outside of equal temperament, you realize that all tonics and other functions within a diatonic scale are not equal. The tonic in D major sounds quite different than the tonic in Eb major, apart form the difference in pitch. It is easy to forget, or perhaps never discover, that these differences exist, because equal tempering causes the notes that establish a tonic to be sterile duplications from one key to another. One of the things I like about fixed do solfege is that calling tonic notes by different names in different keys forces us to think of each tonic as a unique entity, related intervallically and harmonically to the other diatonic tones, but not to tones in other keys Tones that are called by the same name ought to sound the same.
Why don’t all keys sound the same outside of equal temperament? To answer this question, we will look at how pianos are tuned. Today, pianos are generally tuned with equal temperament, meaning the distance between every half step is exactly the same. This eliminates the differences between keys described by many of the classical composers. Well temperament was used by Bach and nineteenth century composers. Well temperament allowed the piano to be played in tune in all keys, but preserved the different character of each key by avoiding equal temperament. Pianos tuned with well temperament, which is not the same thing as equal temperament, are tuned with slower “beats” compared to equal temperament. “Beats” are the oscillations heard when shared overtones between two tones are not perfectly in tune. Slower beats are produced by notes that are less tempered. Tempering is the change from pure tuning. Well tempering creates a tuning where different keys will take on different characters and colors, but will still be useable in all keys. The tuning standard for well temperament is C. With the addition of each additional sharp or flat, more dissonance is introduced. That is why C major is the purest sounding key, and sharp keys are often described as more colorful; they simply have more dissonance built into them.
When a soloist plays with a pianist using an equal tempered instrument, the music can easily sound out of tune because the soloist, if he or she is well trained, will avoid equal temperament as part of his or her collection of expressive performance devices. These notes clash against the equally tempered notes of the piano. This is also why singers and non-keyboard instrumentalists should not learn tuning from a piano. Matching pitch with a piano is destructive to good intonation for a singer or instrumentalist. While equal tempering is necessary for highly chromatic, frequently modulating, and atonal music, it is not necessary for performing music of the standard orchestral repertoire. A more authentic and expressive experience would result from using well tempering for these performances. Ear training in our music conservatories would also be improved with the use of well tempering, and the steady and historical rise in the tuning standard of 440 cycles per second for the tuning note “A” might be stopped or even reversed were well tempering employed, because the richer pallet of timbres musicians seek by playing on the sharp side would be readily apparent from the affects of the tempering. For music teachers, an awareness of the advantages of well tempering, and making use of them in their teaching is certainly worthwhile.