Phonetic symbols in Unicode in the context of "Roundedness"

In linguistics, voicelessness is the property of sounds being pronounced without the larynx vibrating. Phonologically, it is a type of phonation, which contrasts with other states of the larynx, but some object that the word phonation implies voicing and that voicelessness is the lack of phonation.

The International Phonetic Alphabet (IPA) has distinct letters for many voiceless and modally voiced pairs of consonants (the obstruents), such as [p b], [t d], [k ɡ], [q ɢ], [c ɟ], [f v], and [s z]. Also, there are diacritics for voicelessness, U+0325 ◌̥ COMBINING RING BELOW and U+030A ◌̊ COMBINING RING ABOVE, which is used for letters with a descender. Diacritics are typically used with letters for prototypically voiced sounds, such as vowels and sonorant consonants: [ḁ], [l̥], [ŋ̊].In Russian use of the IPA, the voicing diacritic may be turned for voicelessness, e.g. ⟨ṋ⟩.

A syllabic consonant, or vocalic consonant, is a consonant that forms the nucleus of a syllable on its own, like the m, n and l in some pronunciations of the English words rhythm, button and awful, respectively. To represent it, the understroke diacritic in the International Phonetic Alphabet is used, ⟨U+0329 ◌̩ COMBINING VERTICAL LINE BELOW⟩. It may be instead represented by an overstroke, ⟨U+030D ◌̍ COMBINING VERTICAL LINE ABOVE⟩ if the symbol that it modifies has a descender, such as in [ŋ̍].

Syllabic consonants in most languages are sonorants, such as nasals and liquids. Very few have syllabic obstruents (i.e., stops, fricatives, and affricates) in normal words, but English has syllabic fricatives in paralinguistic words like shh! and zzz.

Linguolabials or apicolabials are consonants articulated by placing the tongue tip or blade against the upper lip, which is drawn downward to meet the tongue. They represent one extreme of a coronal articulatory continuum which extends from linguolabial to subapical palatal places of articulation. Cross-linguistically, linguolabial consonants are very rare. They are found in a cluster of languages in Vanuatu, in the Kajoko dialect of Bijago in Guinea-Bissau, in Umotína (a recently extinct Bororoan language of Brazil), and as paralinguistic sounds elsewhere. They are also relatively common in disordered speech, and the diacritic is specifically provided for in the extensions to the IPA.

Linguolabial consonants are transcribed in the International Phonetic Alphabet by adding the "seagull" diacritic, U+033C ◌̼ COMBINING SEAGULL BELOW, to the corresponding alveolar or dental consonant. Pullum & Ladusaw (1996) additionally suggest these sound may be equivalently transcribed with the apical diacritic, U+033A ◌̺ COMBINING INVERTED BRIDGE BELOW, on the corresponding bilabial consonant. However, Olson et al. (2009:64) reject this transcription, as linguolabials may be articulated either apical or laminal. The labial consonants ⟨p᫥, m̼, v̼⟩ have also been used. The choice of the base consonant may depend on whether the author analyses the linguolabial as being phonologically labial or alveolar.

A dental consonant is a consonant articulated with the tongue against the upper teeth, such as /θ/, /ð/. In some languages, dentals are distinguished from other groups, such as alveolar consonants, in which the tongue contacts the gum ridge. Dental consonants share acoustic similarity and in the Latin script are generally written with consistent symbols (e.g. t, d, n).

In the International Phonetic Alphabet, the diacritic for dental consonant is U+032A ◌̪ COMBINING BRIDGE BELOW. When there is no room under the letter, it may be placed above, using the character U+0346 ◌͆ COMBINING BRIDGE ABOVE, such as in /p͆/. However, this has a different meaning in the Extensions to the IPA.