Were church modes commonly used in the middle ages?

Answer 1

In Western Europe in the Middle Ages music was sung in eight different modes, compared to the two that have now (major mode and minor mode). All music at that time was modal, but a great deal of the music that has survived from that time is Catholic church music. The eight modes were still used as late as about 1600, but in the 17th century new styles of composition were limited to major asnd minor modes. So yes, they were not just commonly used but universally used in western Europe.

Answer 2

The easiest way to think of modes is as scales based only on "white notes" of the piano. They all sound different, just as the scale of A minor sounds different from C major. There are seven white notes, A, B, C, D, E, F, G, and each is the basis for a different mode.

The issue is complicated by the fact that the namings of modes changed, and it is also complicated by the fact that the same mode could get different names depending on how it was used.

The modes were called by the names of groups of people known to the ancient Greeks, with the names Lydian, Phrygian, Dorian, Mixolidian, and Locrian, but also Hypolydian and Hypophrigian. These were later changed to include Ionian and Aeolean instead of Hypolydian and Hypodorian, but that came after the Middle Ages

There is a link below to an article on musical modes, where more information can be found.

The reason the modes were used instead of the modern scales, which we seem to regard as so intuitively obvious, is that the ancient and medieval people used integer ratios to divide their scales, and when an instrument is tuned this way to a particular scale, the other scales all have notes that sound out of tune. The change to well tempering required mathematically irrational divisions based in rations involving the twelfth root of two. This was first done in the well tempered scale.

There is also a link to an article on well temperament below.