I am a phonetics layman so I may be using some terms incorrectly. Please do correct me.
According to the IPA chart, /t/ allows multiple tongue positions.
And indeed, whether the tip of my tongue is pressed against my lower teeth, in the gap between my teeth, against my upper teeth, or against the alveolar ridge, I seem to be able to produce the same /t/ sound.
In contrast, /ʃ/ is more restrictively described as post-alveolar according to the chart. However, also here I seem to be able to produce the same sound with multiple tongue positions:
- starting from a post-alveolar position with the front of the tongue bunched up at the palate;
- sliding the tip of my tongue forward until it is between my upper and lower teeth (and un-bunching the tongue); or
- pressing the tip of my tongue against the lower teeth and the blade up behind the alveolar ridge.
This feels particularly off when combined with the flexible /t/. For example, it seems I can pronounce 'change' /tʃeɪndʒ/ in the three ways above where from the first /t/ to the last /ʒ/, the tip of my tongue is
- close to the palate
- between my upper and lower teeth
- against my lower teeth
Am I actually producing subtly different sounds? (If yes, how can they be described/classified?)
How commonly are these variations found? (If uncommon, what are likely explanations if someone used them?)