I was practicing thirds on the violin in E minor this morning, and I noticed when I played (in first position and in tune) a D sharp on the A string and an F sharp on the E string, clearly by all measurements making the interval a minor third, it sounded strangely major. Then I moved my third finger down to the position of D natural, making what would, by all measurements be a major third--and a really "normal" one at that, and it sounded minor in relation to the previous interval.
I pondered this for a long time, and then I finally realized that the whole major-minor flip thing happened because of the excitement of a low B that happens in that register on the violin when the interval is really in tune, which made the minor third between D sharp and F sharp the upper minor third of a B major chord, and the major third between D natural and F sharp the upper major third of a B minor chord.
Overtone excitement is one of the perks of playing in tune.
Tags: Overtones, violin playing