Showing variation of formants of [u:] with context
by Bob Cunningham
These plots were generated to evaluate an assertion that during the pronunciation
of [u:], the tongue moves front to back and then returns to its original position in
the front part of the mouth.
Note that in "roof" and "boob" both F1 and F2 are at a pretty
constant frequency during the pronunciation of the vowel. Greater separation
of first and second formants corresponds to moving the tongue farther front, so
in this case the tongue is not moving.
In the case of "soon", F2 falls at the beginning and rises at the end. This
results in a decreasing, then increasing distance between F1 and F2, which seems
to show that the tongue is first moving back, then front.
The distance between the formants of "room" decreases
during the pronunciation of the vowel, because the frequency of F2 falls.
The decreased spread suggests that the tongue moves farther back.
Except for the vowel in "soon", none of the vowel's formants suggest that there
may be a noticeable backing then fronting of the tongue.
The principal message
carried by the plots is that it's hard to generalize about tongue motion during the
pronunciation of a given vowel. A lot depends upon what the articulatory organs are
doing before and after the vowel.