Hi again,
Ok, sometimes I like to throw ideas at the wall to see what sticks, so do tell
me I talking
rubbish...

Most of English morphology is based on one mouth position. That position is the
blade of
the tongue against the alveolar ridge, with varying movements to make the
sounds. That
position gives /s, z, t, d, n, ŋ, ʃ,ʒ, ʤ,ʧ,l/, move the
tongue down a little bit and you get,
/r/ and a bit more to get /ə/... Those sounds are the basis of English
lexical and
grammatical morphology - past tense, third person, plurals, negatives, 'will'
contractions,
gerunds etc.
Compare how these sounds are produced in other languages:
In Spanish /s, z, t, d/ tend to be dental. In Japanese (not so sure on this
one), they are
produced with the tip of the tongue against the lower teeth.
Go on, try it now, make all the sounds with alveolar, dental and lower teeth
articulation.
With single sounds it's not difficult, but try saying "strength" with a dental
or lower teeth
tongue position.
As an extra twist in the situation, research into casual speech (check out
Shockey 2003,
google it) suggests that these sounds are the ones which are most frequently
changed or
omitted but, from what I could see, only when they are redundant due to other
sounds
(obvious example is "can't" pronounced without a /t/ sound).
So. Does this imply that some form of articulation training would be useful from
early
levels in ELT?