I've noticed in my own speech (West Riding of Yorkshire, male, born in the '90s) two different ways I have of pronouncing phonemes /θ/ and /ð/:
- The tip of my tongue sits in the gap between my top and bottom teeth. Air passes over it and is directed forwards or slightly upwards.
- My tongue sits slightly behind my top front teeth. Air passes between the tip and my top gum and teeth, and is directed significantly downwards as it leaves my mouth.
I can tell the difference between these two methods of pronunciation by putting a finger on the outside of my top front teeth and seeing whether my tongue touches it. I think the rule is that I use method 1 word-initially and at the start of stressed syllables (e.g: “unthinkable”, “overthink”, “Athena”) and method 2 elsewhere.
My questions are:
- Do these methods give rise to acoustically distinct phones? And are they thus allophones?
- Is the distribution of allophones I described above common in English? Are there exceptions among English dialects?