Voiceless velar fricative

The voiceless velar fricative is a type of consonantal sound used in some spoken languages. It was part of the consonant inventory of Old English and can still be found in some dialects of English, most notably in Scottish English, e.g. in loch, broch or saugh (willow).

The symbol in the International Phonetic Alphabet that represents this sound is ⟨x⟩, the X|Latin letter x. It is also used in broad transcription instead of the symbol ⟨χ⟩, the Greek chi, for the voiceless uvular fricative.

There is also a voiceless post-velar fricative (also called pre-uvular) in some languages, which can be transcribed as [x̠] or [χ̟]. For voiceless pre-velar fricative (also called post-palatal), see voiceless palatal fricative.

Some scholars also posit the voiceless velar approximant distinct from the fricative, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɰ̊⟩, but this symbol is not suitable in case of the voiceless velar approximant that is unspecified for rounding (the sound represented by the symbol ⟨ɰ̊⟩ is specified as unrounded), which is best transcribed as ⟨x̞⟩, ⟨ɣ̞̊⟩ or ⟨ɣ̊˕⟩ - see voiced velar approximant. The velar approximant can in many cases be considered the semivocalic equivalent of the voiceless variant of the close back unrounded vowel ⟨ɯ̊⟩.

Features
Features of the voiceless velar fricative:

Occurrence
The voiceless velar fricative and its labialized variety are postulated to have occurred in Proto-Germanic, the ancestor of the Germanic languages, as the reflex of the Proto-Indo-European voiceless palatal and velar stops and the labialized voiceless velar stop. Thus Proto-Indo-European *ḱr̥nom "horn" and *kʷód "what" became Proto-Germanic *hurnan and *hwat, where *h and *hw were likely and. This sound change is part of Grimm's law.

In Modern Greek, the voiceless velar fricative (with its allophone, the voiceless palatal fricative, occurring before front vowels) originated from the Ancient Greek voiceless aspirated stop in a sound change that lenited Greek aspirated stops into fricatives.