When pronouncing the labiodental fricatives [f] and [v], the lip blocks the airflow in the centre of the vocal tract, so the airstream proceeds along the sides instead.
One, found before vowels (and /j/) as in lady or fly (or value), is called clear l, pronounced as the alveolar lateral approximant [l] with a "neutral" position of the body of the tongue.
The other variant, so-called dark l, found before consonants or word-finally, as in bold or tell, is pronounced as the uvularized alveolar lateral approximant [ɫ] with the tongue assuming a spoon-like shape with its back part raised, which gives the sound a [w]- or [ʟ]-like resonance.
In many British accents (e.g. Cockney), dark [ɫ] may undergo vocalization through the reduction and loss of contact between the tip of the tongue and the alveolar ridge, becoming a rounded back vowel or glide.
This process turns tell into [tɛɰ], as must have happened with talk [tɔːk] or walk [wɔːk] at some stage.
A similar process happened during the development of many other languages, including Brazilian Portuguese, Old French, and Polish, in all three of these resulting in voiced velar approximant [ɰ] or voiced labio-velar approximant [w], whence Modern French sauce as compared with Spanish salsa, or Polish Wisła (pronounced [viswa]) as compared with English Vistula.
In central and Venice dialects of Venetian, intervocalic /l/ has turned into a semivocalic [e̯], so that the written word ła bała is pronounced [abae̯a].
In Adyghe and some Athabaskan languages like Hän, both voiceless and voiced alveolar lateral fricatives occur, but there is no approximant.
Some languages have palatal or velar voiceless lateral fricatives or affricates, such as Dahalo and Zulu, but the IPA has no symbols for such sounds.
[citation needed] There are a large number of lateral click consonants; 17 occur in !Xóõ.
Biblical Hebrew may have had non-emphatic central-lateral sibilants [ʃ͡ɬ] and [s͜ɬ], while Old Arabic has been analyzed as having the emphatic central–lateral fricatives [θ͜ɬˤ], [ð͡ɮˤ] and [ʃ͡ɬˤ].