Dental

The fricatives [θ ð] can be made at a couple of places of articulation. For many speakers, the articulation is interdental, i.e. made with the tongue blade between (‘inter-’) the upper and lower teeth. In this case, it may protrude, or be barely visible between the teeth. Such articulations are frequently reported for varieties of American English.

In other varieties, the friction is generated against the back of the teeth and the tongue is held relatively flat so that the air escapes through quite a wide channel. This wide channel is what makes the fricatives [θ ð] so quiet in comparison with [s z]. If you make a [θ] sound and then suck air in, you should be able to feel the place where friction is generated: it is the part of the mouth which goes cold and dry. In the case of dental fricatives, this is a wide area at the front of the tongue.

Some speakers do not use dental fricatives, replacing them with labiodental ones instead, giving  for ‘thing’, for ‘thanks’, [və] for ‘the’, and [fɑ:və] for ‘father’. This phenomenon has gained a lot of attention in sociolinguistic literature and is commonly known as th-fronting.

The sounds [θ ð] are not always produced as fricatives. In some varieties of English, notably some Irish varieties and the East Coast of the USA, they are produced as dental plosives instead, , in all situations. Another possible pronunciation is as an affricate, i.e. a plosive with a fricative release: .

For many speakers, [ð] in particular is highly variable in its manner of articulation, ranging through plosive, nasal, fricative, lateral approximant, and approximant articulations: