This parameter is rather a minor one, since itdistinguishes only one phoneme of English from all others.
For almost allEnglish consonants, the airflow through the oral cavity is central. Recall thatfricatives, like s or f , are produced with close approximation of theactive and passive articulators; however, if you produce any fricative, youwill feel that your articulators are actually pushed together quite tightly atthe sides of the oral cavity, with the actual close approximation, and hencethe narrow gap for airflow, left in the middle. The same is true for all theapproximants except one: if you produce rip and lip, and focus onthe initial consonants, you will notice that while the outgoing air for /r/, asusual, moves along the centre of the mouth, for /l/ it moves down the sides. Ifyou find this difficult to feel, try making the related voiceless fricativesound found in Welsh names spelled with
Alternatively, try making an lingressively, pulling the air into your mouth instead of breathing it out, andfeel the cold air moving inwards along the sides of your tongue. In English,both the clear and the dark allophones of /l/, and only these, have lateralairflow, and are known as lateral approximants. Since the only case where thecentral versus lateral difference is distinctive in English involves /r/ and/l/, these should consistently be described as central and lateralrespectively. Although in a particularly thorough description, all other sounds(except nasals, which have no oral airflow at all) should be explicitly statedto be central, this definition will generally be understood rather than statedbelow, since the other English sounds do not contrast with lateral sounds ofthe same place and manner of articulation, meaning that confusion is highlyunlikely.
