The qualities of musical keys as discussed in Characteristics of Musical Keys always struck me as so much pretense until I had the realization just today that the nature of the intervals from key to key are not precisely the same.
The frequency differences between the notes C and D will remain the same (on instruments where pitches are determined by specific physical placements, as the keys on a piano and the frets on a guitar) but that distance will sound different when it’s between scale degrees 1 and 2 (C Major) and scale degrees 2 and 3 (Bb Major) and scale degrees 4 and 5 (G Major), etc.
Those differences could logically explain how a different feel is possible between different keys and I’m curious now how much validity there is in the subjective characteristics ascribed by music theory for the “color” or “feel” of specific keys.
Can any of you more learned in music theory add to this concept in more or less layman’s terms?
How much of that distinction between C Major and A Minor and Eb Major, etc., be explained by how the intervals differ?
Yes and no. In most modern tunings, the ratio of two frequencies in a half-step is always the same (a factor of 1.05946), so in modern tunings, there really isn’t any “color” to the different keys. Even tempering hasn’t always been used, though: At the time the concept of “key color” originated, the intervals were based on the Circle of Fifths, with the ratios between certain frequencies being simple rational numbers like 4/3 and 5/4. In such a system, the half-step between (for instance) C and C sharp won’t be the same as the half-step between C sharp and D, and it’s those differences that give the different keys their “color”.
There’s no key-color in equal-tempered tunings; all intervals are exactly the same. On other tunings, there is definitely a difference; playing something tuned for one key on an instrument tuned for another can be downright painful. The dissonances are quite obvious in some cases.
There are even-tempered instruments such as piano and guitar. Brass relies on the harmonic series, so when they move aways from their home key they sound odd. Woodwinds… not sure, think they are similar to brass. And for strings, apparently good players can play either even-tempered when paired with a piano, or some sort of natural temperment when playing with voice or each other.
I always thought that this key color was mostly subjective and a lot of nonsense has been written about it. However there are some obvious differences:
major and minor of course.
flat keys are the best keys for brass and woodwinds. Maybe that why some think “rich”, “rustic”, “hunting”, “pastoral”, etc
sharp keys are the best keys for strings. For them you get “bright”, “clean”, “joyous”, etc.