Vowel systems and musical sounds

Would you know of any ready reference that talks about vowels not getting articulated in specific places in the mouth, but rather being part of a system of vowels where the sound value of a vowel is determined by the vowel's relative position of articulation with respect to other vowels? I recall reading about this decades back, most likely, in a book by Henry Sweet.

My renewed interest in the topic is due to the fact that I found something I was looking for for a long time — a recording of a piece of Karnatak music that illustrates this (just the first couple of minutes) — the singer articulates the word paripaalaya in different ways that all make sense, illustrating the above paragraph.

 

I had heard the famous singer, M.D. Ramanathan, sing this in live concerts at about the same time I had read about the vowel systems. I had marveled at how a phonetic observation in a book from one place got illustrated by a piece of music from a very different place. Now thanks to the wonders of www, I can locate the actual piece of music to share!