[asveikau]

> (as opposed to the "th" you would say in "the" which does not use the vocal cords).

Too late to edit, but after saying this out loud a few times I think it's almost always voiced, so maybe a better example is the "th" in "breath" (contrasting with voiced as in "breathe").

[pacaro]

Even just the English names for the letters helps “thorn” and “eth”

IIRC welsh uses a doubled d for the eth sound, hence I once had a coworker whose name was Dydd (pronounced deathe to rhyme with breathe) shortened from Meredydd (usually rendered as Meredith in English)