Voiceless in the context of Voiceless glottal fricative

In phonetics, ejective consonants are usually voiceless consonants that are pronounced with a glottalic egressive airstream. In the phonology of a particular language, ejectives may contrast with aspirated, voiced and tenuis consonants. Some languages have glottalized sonorants with creaky voice that pattern with ejectives phonologically, and other languages have ejectives that pattern with implosives, which has led to phonologists positing a phonological class of glottalic consonants, which includes ejectives.

Modal voice is the vocal register used most frequently in speech and singing in most languages. It is also the term used in linguistics for the most common phonation of vowels. The term "modal" refers to the resonant mode of vocal folds; that is, the optimal combination of airflow and glottal tension that yields maximum vibration.

In linguistics, modal voice is the only phonation found in the vowels and other sonorants (consonants such as m, n, l, and r) of most of the languages of the world, but a significant minority contrasts modal voice with other phonations. Among obstruents (consonants such as k, g, t͡ʃ/ch, d͡ʒ/j, s, and z), it is very common for languages to contrast modal voice with voicelessness, but in English, many supposedly-voiced obstruents do not usually have modal voice.

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.

In phonology, voicing (or sonorization) is a sound change where a voiceless consonant becomes voiced due to the influence of its phonological environment; shift in the opposite direction is referred to as devoicing or surdization. Most commonly, the change is a result of sound assimilation with an adjacent sound of opposite voicing, but it can also occur word-finally or in contact with a specific vowel.

For example, the English suffix -s is pronounced [s] when it follows a voiceless phoneme (cats), and [z] when it follows a voiced phoneme (dogs). This type of assimilation is called progressive, where the second consonant assimilates to the first; regressive assimilation goes in the opposite direction, as can be seen in have to [hæftə].

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.