Contemporary Theories of Tuning Systems in Iranian Classical Music: a Comparative Study

The microtonal intervals and tuning systems in Iranian classical music, which are different from one case to another, have caused much debate among scholars. The contemporary theories may be divided into two categories: experimental studies which calculate the practical intervals of music performance, and the studies that suggest a theoretical system mainly based on medieval theories and deviation from Pythagorean and Just intonation systems. Both kinds of studies demonstrate a wide range of tolerance in intervals. There are many reasons for these deviations that must be taken into account. First, the paper attempts to investigate tuning systems of Iranian classical music based on models of music proposed by contemporary scholars. To this aim, the study summarizes each theory’s assumptions and conclusions. Then, for a better comparison of the theories, the information is sorted in a table based on minor second (about 80-112 cents), minor neutral second (Mojannab) (about 117-151 cents), major neutral second (Mojannab) (about 139-180 cents), major second (about 180-220 cents), and plus-second intervals––an interval between minor third and major second (about 230-94 cents). In contrast to the scholars’ assumption that neutral second is the most flexible interval, it is illustrated that a wide range of fluctuation (about 20-30 cents) occurs in other intervals. These fluctuations are rooted in the factors which are ignored in most of the theories. Finally, this paper illuminates that the following factors play a prominent role in the flexibility of intervals.

a) Acoustical and psycho-acoustical factors: the difference between tone-perception and the real frequency, as well as cultural considerations may affect intervals. Some scholars consider Pythagorean’s pure perfect fifth as a universal preference. Therefore, they extract the intervals based on Pythagoreans’ pure fifths. However, some pieces of evidence reveal that there are many other exceptions, and some of the Iranian classical modes may be considered as exceptions.

b) The school and method of performance: the school in which Persian performers choose to play, affects the intervals.

c) Modes: the intervals are dependent on the modes in which they are played. For instance, the major second in Mahoor is wider than that of Shur.

d) Tonality: to achieve a different color or key character, some performers may use different intervals. For example, D Shure may be performed different from G Shure.

e) Historical considerations: by comparing the recordings, it can be concluded that the intervals have changed during time. For example, the old Isfehan’s leading tone to tonic interval is wider than that of the new Isfehan. Besides, new modalities are formed during the past 100 years that have had an impact on the intervals.

f) Tone function: similar to many string performers who play the chromatic semitones wider depending on the context, Persian players may perform the same interval differently by considering the resolution.

In most cases, the mentioned factors have been ignored by scholars. Therefore, any future attempt to study the practical intervals must take these factors into account. Moreover, a vast number of case studies are required to get reliable results.