Understanding Basic Music Theory - Catherine Schmidt-Jones [88]
This sameness is not true for musical traditions that use modes instead of scales. In these traditions, the mode, like a scale, lists the notes that are used in a piece of music. But each mode comes with a different set of expectations in how those notes will be used and arranged. This module introduces several traditions that are very different from each other, but that are all based on modes or ragas rather than on scales:
the classical Greek modes
the medieval church modes
modal jazz and folk music
Indian classical music
Other Nonwestern modal musics
Although very different from each other, one thing that these disparate traditions share is that the modes or ragas that they are based on are much more variable than the major and minor scales of the tonal system. Figure 6.7 shows one example for comparison. The two major scales use different notes, but the relationship of the notes to each other is very similar. For example, the pattern of half steps and whole steps in each one is the same, and the interval (distance) between the tonic and the dominant is the same. Compare this to the two church modes. The pattern of whole steps and half steps within the octave is different; this would have a major effect on a chant, which would generally stay within the one octave range. Also, the interval between the finalis and the dominant is different, and they are in different places within the range of the mode. The result is that music in one mode would sound quite different than music in the other mode. You can't simply transpose music from one mode to another as you do with scales and keys; modes are too different.
Figure 6.7. Comparison of Scale and Mode
Compare the differences and similarities between the two major scales, and the differences and similarities between the two medieval church modes.
Figure 6.7 shows two scales and two modes. The two major scales use different notes, but the relationship of the notes to each other is very similar. For example, the pattern of half steps and whole steps in each one is the same, and the interval (distance) between the tonic and the dominant is the same. Compare this to the two church modes. The pattern of whole steps and half steps within the octave is different; this would have a major effect on a chant, which would generally stay within the one octave range. Also, the interval between the finalis and the dominant is different, and they are in different places within the range of the mode. The result is that music in one mode would sound quite different than music in the other mode. You can't simply transpose music from one mode to another as you do with scales and keys; modes are too different.
The Classical Greek Modes
We don't have any recordings of ancient music, so we do not know exactly what it sounded like. But we can make some educated guesses as to what music from ancient Greek and Roman times really sounded like, based on their writings. We know, for example, that they used modes based on tetrachords, mini-scales of four notes, in descending pitch order, all contained within a stretch of a perfect fourth. We have very detailed descriptions of tetrachords and of Greek music theory (for example, Harmonics, written by Aristoxenus in the fourth century B.C.).
The perfect fourth is an interval that occurs naturally, for example in string and wind instrument harmonics (see Standing Waves and Musical Instruments for more on this), so we can be pretty certain that we understand that part of ancient Greek music theory. It is more difficult to be certain of the exact tuning of each note within a tetrachord. Enharmonic tetrachords are particularly confusing; it is clear that two of the notes were very close in pitch. As shown in Figure 6.8, they are often notated so that, using modern tuning, the two notes would sound the same. This sameness is a result of equal-tempered tuning, however; other tuning systems have been used which cause enharmonic notes to be tuned slightly differently. (See Tuning Systems for more about this.) It is not clear whether