by Cliff DeArment
There are two predominant scales in traditional Indonesian music, Slendro and Pelog. Each has a unique character identified by the intervallic relationships between tones. Though both of these scales vary considerably in actual measurement from one gamelan to another, their basic form is consistent throughout Indonesia and much of S.E. Asia.
In common practice, Slendro is a five tone scale consisting of, approximately, whole step and minor third intervals. The basic order of intervals from low to high, where 2 equals an approx. whole step and 3 equals an approx. minor third, is 2 3 2 2 3. This scale is said to be derived from an equidistant ten tone master scale. This ten tone scale is never played as such and only serves as a basis for scale theory. A few different combinations of the ten tones may be derived which sound like Slendro, but each will have a slightly different character which may be best suited for one "modality" (term used loosely) or another.
When building a Gamelan, one of these derivations is chosen as best suited for it's purpose and the maker must commit to that interpretation of the Slendro scale. Every tuner also has their own preferences within those derived scales, adding to the wide variety of interpretations of both Slendro and Pelog from Gamelan to Gamelan. String, vocal, and wind instruments have the ability to transcend this limitation and explore other interpretations of the scale by virtue of their unfixed pitch.
Pelog is a seven tone scale, although only five of the seven pitches are typically used at one time. Pelog may also originate from the ten tone master scale mentioned above. The basic seven intervals, where 1 equals an approx. half step, 2 equals an approx. whole step, and 3 equals an approx. minor third, are 1 2 3 1 1 2 2. There are wide variations of Pelog. Some may be closer to the intervals 2 1 3 1 1 2 2.
In real practice, Pelog is best described as a combination of mostly approx. half steps and major thirds. The presence of a half step, or lack of it, is an easy indicator for distinguishing by ear between Pelog and Slendro. If we number the pitches 1 through 7, the actual five tone Pelog scales used in Gamelan are predominantly 1 2 3 5 6, 1 2 4 5 6, and 2 3 5 6 7. Calling an approx. major third 3+ and a near fourth 4, this gives intervallic relationships of 1 2 3+ 1 3+, 1 4 1 1 3+, 2 3+ 1 2 2, respectively. These scales sometimes intermesh and overlap, particularly in Java. Balinese pelog is also theoretically seven tones, but most instruments only have the pitches 1 2 3 5 6 available. There are only a few types of Balinese instruments capable of producing seven tones, mostly classical ensembles, such as Semar Pegulingan and Gong Suling, not in great use anymore. Playing these intervals on a piano or other instrument, if no gamelan is available, can help to gain a sense of the character of the different scales and how the pitch substitutions occur.
Which came first? Slendro or Pelog?
There is no conclusive proof to say which scale was introduced first or if they may have arisen concurrently. The commonly held belief in Indonesia is that Slendro is the predecessor. Slendro is the primary scale for all of the oldest rites of importance including shadow play in both Bali and Java. The previously mentioned ten tone master scale is sometimes referred to as Slendro but usually not Pelog. Both share a common origin, so it doesn't really matter too much which was first to be accepted. By population statistics it would appear that Pelog is actually the elder scale as it is in some ways more popular and wide spread. If we assume that usage density and dispersion equals age, this may be true. Debates will likely continue on this matter as long as there is an interest in Indonesian music.
The Origins of Indonesian Scales
Indonesian scales and systems have many roots, some from China, others from India, and others from the islands themselves. Chinese influences are best seen in the structure of the scales, while the Indian influence is more obvious in how the scales are utilized.
One strong link to China is the intervallic shape of the Slendro scale which is very close to common scales of the mainland.
Another China link, although not so apparent, is the Huang Chong. The Huang Chong is an instrument of pitch measurement. It consists of a stopped bamboo tube of specific length and girth which is blown across the end to produce a set standard pitch and harmonics from which other music is to be derived. The pitch of the Huang Chong, 366hz, is common within a few cents, to a pitch in most Slendro Gamelan, usually pitch 3 in Java and pitch 2 in Bali. Most Gamelan makers today may not realize that they use it at all and the Huang Chong is not a hard and fast rule. In fact, many Gamelan have no pitches anywhere near 366hz. It is explored only as a matter of historical reference.
To best observe India's
influence on the use of scales in Indonesia, it helps to have a cursory understanding
of the "modal" systems called Patet in Java and Saih in Bali. The Indian Raga
system is a set of rules of motion, often ascending the scale in one form and
descending with a different set of pitch options. Indonesia has only a descending
rule for each "mode." This descending pitch motion is what defines the "mode."
It contributes greatly to the musical effect of "falling" to key structural
points or gongs. The word mode appears in quotes because it is a misleading
term if used in the western sense. Indonesian "modes" are actually more like
treatments of scale, rather than a set of pitches starting on a certain tone.
Patet and Saih are sets of pitches *ending* on a certain tone and getting there
in a particular way. Path + Destination = Patet/Saih.