Voiced TH phoneme /ð/

Phoneme /ð/ is a consonant phoneme that’s one of the standard English phonemes.

Pronunciation

The standard pronunciation of this phoneme is as a voiced dental fricative [ð].

Speakers with th-substitution substitute this in various ways. Those with th-fronting substitute a voiced labiodental fricative [v]; those with th-stopping substitute it with a voiced alveolar plosive [d]. It’s quite common for EFL learners to substitute /ð/ with a voiced alveolar sibilant [z], which is th-alveolarisation, especially those from France or China.

This phoneme is not part of the lingua franca core, and substitution of it should not seriously impede intelligibility.

Spelling

Spelling is consistently ⟨th⟩ — though that can code for other phonemes, particularly phoneme /θ/.

Phonogram	Subset	Words	Notes
⟨th⟩	Grammar words	the, that, this, there, these, those, then, though, than, with
	Verb codas	breathe, clothe, bathe, mouth, sooth, smooth.
	Before ⟨er⟩	altogether, another, bather, blather, brother, either, father, farther, feather, further, heather, lather, leather, mother, neither, other, rather, soother, slither, smoother, tether, together, weather, wether, whether. (but not ether.)
	Voiced plurals	baths, mouths, truths, youths	May be pronounced either way.
	Oddities	lathe, booth
⟨dd⟩	Welsh words	Bleddyn, Dafydd, Eisteddfod, Gwynedd, Pontypridd