Voiceless uvular fricative
The voiceless uvular fricative is a type of consonantal sound used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨χ⟩, the Greek chi. The sound is represented by ⟨x̣⟩ (ex with underdot) in Americanist phonetic notation. It is sometimes transcribed with ⟨x⟩ (or ⟨r⟩, if rhotic) in broad transcription.
|Voiceless uvular fricative|
There is also a voiceless uvular fricative trill (a simultaneous [χ] and [ʀ̥]) in some languages, e.g. Hebrew and Wolof as well as in the northern and central varieties of European Spanish. It can be transcribed as ⟨ʀ̝̊⟩ (a devoiced and raised uvular trill) in IPA. It is found as either the voiceless counterpart of [ɣ] or the sole dorsal fricative in Northern Standard Dutch and regional dialects and languages of the Netherlands (Dutch Low Saxon and West Frisian) spoken above the rivers Rhine, Meuse and Waal (sometimes termed the Rotterdam–Nijmegen Line). A plain fricative that is articulated slightly further front, as either medio-velar or post-palatal is typical of dialects spoken south of the rivers (mainly Brabantian and Limburgish), including Belgian Standard Dutch. In those dialects, the voiceless uvular fricative trill is one of the possible realizations of the phoneme /r/. In fact, more languages claimed to have a voiceless uvular fricative may actually have a fricative trill. Ladefoged & Maddieson (1996) note that there is "a complication in the case of uvular fricatives in that the shape of the vocal tract may be such that the uvula vibrates."
The frication in the fricative trill variant sometimes occurs at the middle or the back of the soft palate (termed velar or mediovelar and post-velar, respectively), rather than the uvula itself. This is the case in Northern Standard Dutch as well as some varieties of Arabic, Limburgish and Madrid Spanish. It may thus be appropriate to call those variants voiceless (post)velar-uvular fricative trill as the trill component is always uvular (velar trills are not physically possible). The corresponding IPA symbol is ⟨ʀ̝̊˖⟩ (a devoiced, raised and advanced uvular trill, where the "advanced" diacritic applies only to the fricative portion of the sound). Thus, in cases where a dialectal variation between voiceless uvular and velar fricatives is claimed the main difference between the two may be the trilling of the uvula as frication can be velar in both cases - compare Northern Dutch acht [ɑʀ̝̊˖t] 'eight' (with a postvelar-uvular fricative trill) with Southern Dutch [ɑxt] or [ɑx̟t], which features a non-trilled fricative articulated at the middle or front of the soft palate.
For a voiceless pre-uvular fricative (also called post-velar), see voiceless velar fricative.