How to tell apart theta θ and eth ð
It’s easy to find words that distinguish between other voiced/voiceless pairs in English - bus and buzz, fine and vine - but the two sounds represented by the “th” sequence in English are rarer and harder to learn, especially since English uses the same spelling for both of them.
A lot of people give up and just use near-minimal pairs like “think” and “this”, or “theta” and “they”, but there are actually a few true minimal pairs that you can use:
thigh - thy ether - either thistle - this’ll
It’s worth noting that function words in English, like pronouns, prepositions, and determiners, tend to have ð, while content words, especially nouns, tend to have θ.
Theta θ and eth ð are also found in the following noun/verb minimal pairs, at least for many dialects:
wreath - wreathe
(I put a wreath on the door / I wreathe the door)
teeth - teethe
(my teeth / the baby is teething)
loath - loathe
(I’m loath to do it / I loathe doing it)
sheath - sheathe
(in a sheath / to sheathe one’s sword)
sooth - soothe
(for sooth! / to soothe someone)
Here the vowels differ, but the theta θ to eth ð, noun to verb relationship is preserved:
cloth - clothe
(wear cloth / clothe oneself)
bath - bathe
(take a bath / bathe the baby)
breath - breathe
(take a breath / breathe deeply)
Make sure to try them at full volume, not whispering, because whispering involves turning off your vocal cords (which is why you can whisper when they’re inflamed with laryngitis).
These sounds are called dental fricatives or interdental fricatives, because the sound is produced by a thin stream of air friction where the tongue is at (dental) or between (interdental) the teeth. In the International Phonetic Alphabet, the voiceless interdental fricative, theta, is written θ, and the voiced interdental fricative, eth, is written ð.
As a bonus, here’s a minimal pair for ʒ and ð, thanks to recent developments in clothing technology: pleasure and pleather.
