I overheard that indian music disputes the notion that 7 notes are equally divided. Hence, people should use tanpura (instead of harmonium or piano) to practice with. I googled about it, and I read that it only plays Pa Sa Sa Sa (or something like that). Can anybody shed light on the topic? Does anybody know some online tanpura that can play all 7 notes? (else how is one supposed to practice?)
See here to play a virtual live tampura and to read more about it.
As you'll find in text:
Having reference tone playing in the background can come in real handy here to help the bansuri player stay on pitch. Tanpura serves this purpose very well as it not only provides the root note Sa but Pancham or Pa (the fifth note) as well. Besides these, Tanpura produces a whole repertoire of rich harmonics (jawari in Hindi).
Also you'll find it helpful to read about quarter tone which is a basic component of many countries' traditional music in Middle-east and Central Asia. As you may know even having smaller note divisions in music of some countries is common.
You can watch a man playing quarter tones here.
The tambura creates a harmonic or resonance field based on the three notes, sa (first), pa (fifth) and higher sa (an octave above first sa) and their OVERTONES. A singer orients himself to these notes and places the other notes by listening for harmonic resonance. This can be done very easily or can take a long while to learn depending on the skill of the musician.
The octave is an artificial creation. That is why the piano is tempered (adjusted) to create equidistant notes.
I play piano and sing Indian music, and am finding very slight nuance differences in pitches because of how the harmonics are tempered (adjusted deliberately) in the piano versus the unadjusted harmonics of the tambura created by 3 notes. The differences are small and not too important, except it makes me ear training a bit more complicated. My ear seems to hear the differences even if I can't hear them, if that makes sense.
Western music is based on the tempered scale because it helps with all kinds of things to do with chords and scales. Indian music relies on natural harmonics even if the notes are not equidistant. Indian music doesn't use chords so they don't worry about that problem.
I hope this helps.
I overheard that Indian music disputes the notion that 7 notes are equally divided.
Indian Music is broadly classified into two traditions - the North Indian and the South Indian. The rules are slightly different in both these traditions.
Just like Western music, Indian music also divides the octave into twelve notes (called swaras). But the notes are not tuned in the chromatic scale. Instead of an equally tempered intervals Indian music theory uses the concept of a shruti, which is an interval smaller than the intervals as used in Western Music. This wikipedia article gives a breakup of the frequency for different shrutis as used in South Indian music. For example, in the article, see how there is an intermediary interval say between C and C#.
A much more detailed description of this system can be found in this Rice university article.
Regarding your second question, Tanpura strings have a very rich overtone which is the reason why Tanpura is recommended for practice (instead of harmonium or piano). If you are interested in knowing more about the usage of Tanpura in Indian classical music, I highly recommend this 10 minute video by Pandit Ajoy Chakraborty who is a renowned maestro of Indian classical music.
If you want to experiment for yourself, here is a Virtual tanpura where you can change the pitches. Note however that while this online tanpura allows you to change the first string to just about any note, in practice the first string is tuned mostly to pa and occasionally to ma for certain that(that in Indian music is akin to scales in Western Music .But while there are two main scales - Major and Minor, there are more than 20 that in North Indian system of Music).