One of the underlying techniques in the production of vowel sounds – such as present in “oooh” “aaaaah” “eeeeh” etc – is to raise the tongue root. But how is this actually accomplished in practice? Answers were provided courtesy of the linguistics department of the City University of New York, in 1977 – at the CUNY linguistics conference.
“Physiologically, one of the means to raise the tongue is to pull the root of the tongue forward, since, as an incompressible body of constant mass, if the tongue is constricted in one area it will expand in another.”
See: Issues in vowel harmony : Proceedings of the CUNY linguistics conference on vowel harmony, 14th May 1977 (page 185) edited by professor Robert Vago