Do capable harmony singers sing in just intonation or tempered tuning?

Question

Given that the human voice is capable of microtonal adjustments to an infinite degree and not limited by the fixed tuning imparted upon an instrument such as a piano - I am wondering if singers who harmonize with the lead vocalist subconsciously adapt and instead of singing a equal tempered third or fifth actually sing something closer to a justly intoned harmonically natural interval. If this does occur, it might help explain why some singers sound so incredible harmonizing together. I have been privileged to hear some performances where the vocal harmonies actually gave me shivers up and down my spine and seemed to touch my soul with their sensual richness. **Have there been any studies (or is there compelling evidence) which attempt to ascertain if trained and capable singers who sing harmony - instinctively gravitate towards pure intonation verses singing the notes they have learned to associate with equal temperament tuned instruments?** In other words if they are singing a fifth above, would the instinctive control center of their brain override their musical training and adaptation and lead them towards singing a perfect natural fifth or would they sing something closer to a equal tempered fifth that a piano would play?

Answer 1

Just intonation. Unless they're so thoroughly trained in piano, or singing to piano accompaniment (and untrained in vocal harmony) that they are just used to singing in even-tempered intonation. So, the singer's experience can dictate the answer to your question. But, in my mind, and as a brass player, there's no question that striving for just intonation delivers the best-sounding harmonies, both vocally and instrumentally.

Answer 2

You are right you shall always follow the leader as a backing singer. Therefore if the singer is slightly out of tune the backing singer would follow. But if the lead singer is way out of tune then the backing singer should aim to stay in tune so that the lead singer can get back in tune. This only applies to live performances, in a studio everything is now tuned with the computer unless you're Beyonce, she sings in tune 99% of the time and her vocal almost never need tuning. As for studies to get really good at harmonizing you'd want to work on ear training!