Editing Approximant (section)

=== Phonetic characteristics ===
[[Fricative]] consonants are generally said to be the result of turbulent airflow at a place of articulation in the vocal tract.<ref>{{Harvcoltxt|Ashby|Maidment|2005|pp=56–7}}</ref> However, an audible voiceless sound may be made without this turbulent airflow: {{Harvcoltxt|Pike|1943}} makes a distinction between "local friction" (as in {{IPA|[s]}} or {{IPA|[z]}}) and "cavity friction" (as in voiceless vowels like {{IPA|[ḁ]}} and {{IPA|[ɔ̥]}}).<ref>{{Harvcoltxt|Pike|1943|pp=71, 138–9}}</ref> More recent research distinguishes between "turbulent" and "laminar" airflow in the vocal tract.<ref>{{Harvcoltxt|Shadle|2000|pp=37–8}}</ref> It is not clear if it is possible to describe voiceless approximants categorically as having laminar airflow (or cavity friction in Pike's terms) as a way of distinguishing them from fricatives. {{Harvcoltxt|Ball|Rahilly|1999}} write that "the airflow for voiced approximants remains laminar (smooth), and does not become turbulent. Voiceless approximants are rare in the languages of the world, but when they do occur the airflow is usually somewhat turbulent."<ref>{{Harvcoltxt|Ball|Rahilly|1999|pp=50–1}}</ref> Audible voiceless sounds may also be produced by means of turbulent airflow at the glottis, as in {{IPA|[h]}}; in such a case, it is possible to articulate an audible voiceless sound without the production of local friction at a supraglottal constriction. {{Harvcoltxt|Catford|1977}} describes such sounds, but classes them as [[sonorant]]s.<ref>{{Harvcoltxt|Catford|1977|pp=122–3}}</ref>