Assamese

Assamese is an Indo-European language (Indo-Aryan branch) spoken by approximately 20 million people in India and Bangladesh.
Assamese has eight vowels. Of particular interest is the contrast between the lower-mid and low back vowels. Superimposed FFT-LPC spectra for these two vowels are included here for comparison.

The spectra show analyses of the two vowels [ɔ] and [ɒ̹]. The first is fairly similar to the IPA reference vowel [ɔ]; the second has a tongue position like that of [ɒ], but with a lip position more like that of [u]. The first and second formants are at slightly higher frequencies for [ɔ] - an unusual situation in that higher vowels normally have lower first formant frequency. The considerable rounding in [ɒ̹] has caused both formants to be lower as well as a very sharp decrease in spectral energy immediately above the second formant.