Variable tongue position for /ʃ/ and /tʃ/

Question

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?)

Answer 1

We would have to somehow inspect your articulations and record the sounds that you make to see if your description is accurate, and that's probably impractical. I think it is most likely that you are producing different sounds and you just don't notice the difference, since they don't necessarily correspond to anything linguistically distinctive in a particular dialect of English. It is well-known that speakers of English vary substantially in their articulations of lingual consonants, yet we hardly notice the consequences since we only have to worry about one kind of "t". We have θ, s and ʃ to worry about, but if you consider the range of lingual fricatives out there ("s" in northern Spain; Ron Silver's peculiar "s"), again we just put everything on one of those categories, and don't notice exotic sounds like ʂ, ç, ɕ and related sub-variants as found in other languages.

The system of classification in the IPA is fundamentally designed to classify the sounds of language with a set of symbols and classifications of sound-distinctions known to be phonemically contrastive in at least one language, and is supplemented with diacritics to specify further phonetic detail. It is not designed to precisely describe an individual's idiosyncratic (non-systematic) articulatory path.

The premise of a linguistic treatment of sounds is that they are in some context stable and replicable. If you reliably produce your "s" as [s̻] and your "sh" as [s̺] then we cal collect a bunch of samples and see if people can hear the difference – but the people we ask are not folks off the street, they would be trained phoneticians. If the trained phoneticians cannot reliably distinguish two sub-type of fricative, then we would be hard-pressed to say that there are two (or more) phonetic categories. However, trained phoneticians can distinguish the myriad phonetic subtypes of "ʕ" as exist in Salishan, Tigrinya, Somali, Arabic and Chechen. Even though Salishan and Arabic have phonetically different consonants [ʕ], they can be distinguished by someone has the relevant experience (unfortunately, a diminishing skill in the profession).

In other words, the question is answerable in principle, but not on the internet.