Apart from western music, in which chord shifts have become a standard and for which the tempered scale with its 12 fixed semitones equally spaced within an octave was created in the 18th century, listening to most of the traditional music from around the world, we find different scales that use unequal intervals within the octave. This type of music is often referred to as modal and the microtonic variations are very much part of what engenders different moods for the artist and the listener, and also defines the special character of each musical culture. The untempered scale is most natural to the human voice, in speech or song, and through the ages numerous instruments have been invented which in some way (more or less) recall the voice. This is especially true in India, where the sliding or bending of notes is a most typical feature.
Often referred to by musicologists as the just intonation scale, Indian music has a well-defined set of 22 intervals (shrutis) within the octave, and the Indian musician singing or playing a raga, whether in pentatonic or septonic or any other mode, uses these microtones as pivot points, often moving freely between two notes as a kind of infinitely exploitable space, eventually returning home to the tonic Sa.
In Indian musical theory, it is said that in the parent 7-note modes, where the 2nd ,3rd,4th, 6th and 7th notes are variable, the 1st (Sa or Do) and the perfect 5th (Pa or Sol) are immutable and of a fixed pitch.
The drone is accordingly often Do-Sol (Sa-Pa), which becomes the ultimate open chord containing all other notes within it as a series of subtle harmonics.
This drone (a constant note or tonic), whether actually played on an instrument like the tampura or simply heard within oneself as the Om sound, is the constant reference without which no Indian musician would play.
While most western string instruments are tuned in a way, which follows the tempered system, they do not give a very harmonious sound when all strings are struck openly. Indian string instruments, on the other hand, which are generally tuned in 5ths or 4ths, create a pleasant, harmonious sound when struck openly.
These are just a few basic principles which lie at the root of Indian music and, even though my music is not traditional, I have found them indispensable in my creative and learning process throughout the years.
About 25 years ago, when I encountered everything Indian with enthusiastic admiration, I was introduced to Carnatic music (South India) through the veena and later to Hindustani music (North India) through the sarod. Though I did enjoy playing these great instruments, I would often go back to my original instrument, the guitar, with a basic question in mind: Could Indian music be played on the guitar? Over the years, the answer gradually revealed itself: Why not! But, certainly not without modifications.
And matters gradually evolved as follows. When trying different open tunings, I eventually found a way, which in retrospect seems to me quite obvious, and tuned my guitar in 5ths, as Do-Sol-Do-Sol-Do-Sol (from lowest to highest string).
Later on came the more radical step of modifying the neck, or scalloping in technical terms, which consists in carving out some of the wood between the frets. The objective of this is to ensure that the fingers, when pressing the strings, do not come in direct contact with the wood of the fretboard. This makes it easier to stretch the strings, especially when the string action is high and the strings, as I prefer them to be, are thick and tight. In the late 1970s, John McLaughlin had already successfully introduced this unique feature with one of the custom-built guitars on which he performed, recording three albums with his group Shakti ; these soon became milestones of East -West fusion.
The most unusual feature of my instrument is the mobile frets. While redesigning a completely new neck for a second-hand American guitar made in the 1950s, selecting for it a deep, rich tone, the following idea came to me: Why not find a way to make the fret positions adjustable, like those of the sitar, so that I could attempt to reach more accurately the microtones of Indian modes and also play chords that are in tune with these modes?
Having myself had a fair amount of practical experience in woodwork, and with the advice of a friend who had had practical training in guitar making, we embarked on this odd plan and, together with a local carpenter, eventually made it work. In the process we were even able to make the neck hollow.
After a trial period and with certain adjustments, being satisfied with the positive result, I eventually carved out the wood between the frets into smooth curves, thus also making it scalloped.
Some years later, I added two small drone strings (chikari), tuned Do-Sol, as on the sitar, sarod or veena, which are struck rhythmically with the right hand.
As to the etymology of the word guitar, the origin of the Sanskrit syllable "guit" means, song; the syllable "tar", though often attributed to the Greek language, in fact goes further back in time to the Sanskrit word meaning string for example, ektar (with one string) or sitar (many strings). And, that was a brief description of my Indian Geet-Tar.