Voice or voicing is a term used in phonetics and phonology to characterize speech sounds (usually consonants). Speech sounds can be described as either voiceless (otherwise known as unvoiced) or voiced.
The term, however, is used to refer to two separate concepts:
Nasal clicks are click consonants pronounced with nasal airflow. All click types (bilabial ʘ, dental ǀ, alveolar ǃ, lateral ǁ, palatal ǂ, and retroflex 𝼊) have nasal variants, and these are attested in four or five phonations: voiced, voiceless, aspirated, murmured (breathy voiced), and—in the analysis of Miller (2011)—glottalized.
In Semitic linguistics, an emphatic consonant is an obstruent consonant which originally contrasted, and often still contrasts, with an analogous voiced or voiceless obstruent by means of a secondary articulation. In specific Semitic languages, the members of the emphatic series may be realized as uvularized, pharyngealized, velarized or ejective, or by plain voicing contrast; for instance, in Arabic, emphasis involves retraction of the dorsum (or root) of the tongue, which has variously been described as velarization or pharyngealization depending on where the locus of the retraction is assumed to be. The term is also used, to a lesser extent, to describe cognate series in other Afro-Asiatic languages, where they are typically realized as ejective, implosive or pharyngealized consonants.
In Semitic studies, emphatic consonants are commonly transcribed using the convention of placing a dot under the closest plain consonant in the Latin alphabet. However, exceptions exist: original emphatic k developed into /q/ in most Semitic languages; strictly speaking, it has thus ceased to be an emphatic version of k and has become a different consonant, being most commonly transcribed as q (rather than ḳ) accordingly.
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