Mick wrote:
I think the difference is that the a in amhras is a kind of nasally "ow" sound, spoken through the nose as if you've got a slight cold. Abhras is similar, but there is no nasal quality to the "ow."
But a lot of dialects have lost the nasal vowels, so words like abhras and amhras often sound the same nowadays.
Of course you are correct, traditionally one had a nasal "ow" sound and the other didn't.
However nowadays, as you said, the distinction is quite rare. I haven't heard it in Cork. Brian Ó Cuív said (in 1944) that it was feature of previous generations. It was already "half-gone" in the generation born in the 1870s. However it's still around in Kerry, I heard the nasal vowels from a few people in Kerry, near Dún Chaoin, not the rest of the peninsula though.
I'll have the new notes up tomorrow, hopefully not too late. I'll also update the old ones with Bríd's translation.