Also asked, do singers sing in just intonation?
Singers will tune to whatever is around them. If that's instruments in 12-TET, that's what they'll tune to. If it's a choir, they will probably tend to harmonise in just intonation, and also follow each other if they tend to drift flat or sharp from any initial reference pitch.
One may also ask, is Pythagorean tuning just intonation? In Pythagorean tuning, which was wedded to Pythagorean philosophy and thus to an expression of ratios within the three-limit system, all the intervals of the scale had to be derived, as we saw in the last page, from perfect fifths, the 3:2 ratio. In Just intonation, we add the ratios that include the numbers 5 and 6.
Similarly one may ask, is just intonation better?
Some people describe harmonies in Just Intonation as being "full" or "rich", while others describe them as "bland" or "lifeless". However, most people would agree that JI harmonies are considerably smoother than tempered harmonies.
What instruments use just intonation?
The modern un-fretted bowed string instruments; the violin, viola, cello and bass, can and do play in just intonation and can modulate to any key center and maintain just intonation. Modern brass instruments without valves, such as the bugle, play in just intonation in one key only.