This is fascinating. Thank you for commenting. As an Indian living in the West, I have always wondered why/how certain differences that are stark to my ears are subtle or barely perceptible to others.
The converse is also true. For example, the way native Swedish speakers pronounce seven (sju - example pronunciations at https://forvo.com/word/sju/ ) is 1) Hard for me to say and 2) No matter how I say it, the response from Swedes is, "You said <X>; it's actually <X1>" where both <X> and <X1> sound exactly the same to me, so I don't hear the distinction they are trying to point out. I assumed the same happens to Western folks when Indians/Hindi speakers try to explain the difference between the various T sounds.
> The bigger issue is English lacks a retroflex plosive (tongue curls), and aspiration is non-phonemic (does not carry a meaningful distinction)
But English words do seem to distinguish meaningfully between what you term 'voiceless' and 'aspirated voiceless' isn't it? For example, there is a difference between 'time' and 'thyme'. Ignoring the difference between 'y' and 'i' for a moment, wouldn't both words be the "same" to English speakers if what you are saying is true? Isn't 'th' just the aspirated version of 't'? (Not contesting what you are saying, just curious to understand.)
"Thyme" is odd because it used to be spelled "tyme" in Middle English (1066-1400s). I assume it was changed to 'th' to be more similar to Latin and French. Something similar happened to "island" (iland) and "isle" (ile) where a silent 's' was added to make the words closer to the Latin "insula".
> But English words do seem to distinguish meaningfully between what you term 'voiceless' and 'aspirated voiceless' isn't it? For example, there is a difference between 'time' and 'thyme'. Ignoring the difference between 'y' and 'i' for a moment, wouldn't both words be the "same" to English speakers if what you are saying is true?
Aspiration is not contrastive in English - it's impossible to find two words that differ only by aspiration. Aspirated consonants (in general American English) mainly feature in the onset of a stressed syllable (pin ['pʰɪn], potato [pə̥ˈtʰeɪɾoʊ]) as long as they're not preceded by /s/ (spin ['spɪn]). The important part is that you can determine whether or not a consonant is aspirated only by its position in the word, which is why it's an allophone - a variation of a phoneme which isn't distinctive, but still sounds different. English is my L2 so "thyme" still messes me up, I always try to pronounce it with /θ/ like the first consonant in "thigh".
How people differentiate sounds is actually very interesting. The leading theory is that infants can differentiate all human phonemes (see Jusczyk's Head turn Experiment) but starts categorizing sounds into categories based on what languages are spoken to them by 9-12 months. An interesting language is the (sadly extinct) Ubykh, which had 84 (!) phonemic consonants but only 2 or 3 distinct vowels. For example, speakers percieved /qʲ q qʷ qˤ qˤʷ/ as five different sounds, even though an English-only speaker would probably categorize all of them as just "kinda guttural".
On "sju" (/ɧʉː/) - /ɧ/ is a very odd sound in general. It doesn't really feature in any other languages, and what exactly it should be categorized as is still debated by phoneticians. It also varies a lot by region - Finland Swedes generally don't differentiate the consonants in "sju" and "köpa". So bottom line, we don't know how to pronounce it either :D
> For example, there is a difference between 'time' and 'thyme'. Ignoring the difference between 'y' and 'i' for a moment, wouldn't both words be the "same" to English speakers if what you are saying is true?
But they are the same; both are pronounced (in traditional IPA) as /taɪm/
There is no difference in pronunciation between time and thyme. Both will be pronounced with the same amount of aspiration. Why English maintains a th- spelling for some words of Greek and Latin origin instead of plain t- is a long story, but in English it makes no difference in pronunciation.
The converse is also true. For example, the way native Swedish speakers pronounce seven (sju - example pronunciations at https://forvo.com/word/sju/ ) is 1) Hard for me to say and 2) No matter how I say it, the response from Swedes is, "You said <X>; it's actually <X1>" where both <X> and <X1> sound exactly the same to me, so I don't hear the distinction they are trying to point out. I assumed the same happens to Western folks when Indians/Hindi speakers try to explain the difference between the various T sounds.
> The bigger issue is English lacks a retroflex plosive (tongue curls), and aspiration is non-phonemic (does not carry a meaningful distinction)
But English words do seem to distinguish meaningfully between what you term 'voiceless' and 'aspirated voiceless' isn't it? For example, there is a difference between 'time' and 'thyme'. Ignoring the difference between 'y' and 'i' for a moment, wouldn't both words be the "same" to English speakers if what you are saying is true? Isn't 'th' just the aspirated version of 't'? (Not contesting what you are saying, just curious to understand.)