I can not remember, but he did mentioned an ancient sect in Gujarat who for thousands of years have earnestly adhered to the principle of correct utterance of a hymn or Mantra. I will be glad if you share more on this. If not here then feel free to mail me at firstname.lastname@example.org. Because this is one of my intense interests.
I first came to know about this when I read about a memoir written by a Vedic Scholar, Shailendra Narayan Ghoshal Shastri who after demise of his father (who was also a tremendous scholar on Hinduism and a Yogi) travelled Narmada river in the 50's.
I would love to read about more about it, IFB. What you wrote during our conversation actually quite profound. There are different sects situated both in Northern and Southern India (Strangely they are not found in Bengal where the worshipping of Shakti is in dominance) who strenuously emphasize on proper pronunciation hymns. There are also sects who stress on the meaning of the hymn and not on pronunciations.