Interdental

Interdental consonants are produced by placing the tip of the tongue between the upper and lower front teeth. This differs from dental consonants, which are articulated with the tongue against the back of the upper incisors.

Interdental consonants may be transcribed with both a subscript and a superscript bridge, as ⟨n̪͆ t̪͆ d̪͆ θ̪͆ ð̪͆ r̪͆ l̪͆ ɬ̪͆ ɮ̪͆⟩, if precision is required, but it is more common to transcribe them as advanced alveolars, as ⟨n̟ t̟ d̟ θ̟ ð̟ r̟ l̟ ɬ̟ ɮ̟⟩.

Interdental consonants are rare cross-linguistically. Interdental realisations of otherwise dental or alveolar consonants may occur as idiosyncrasies or as coarticulatory effects of a neighbouring interdental sound. The most commonly occurring interdental consonants are the non-sibilant fricatives (sibilants may be dental, but do not appear as interdentals). Apparently, interdentals do not contrast with dental consonants within any language.

Voiced and voiceless interdental fricatives [ð̟, θ̟] appear in American English as the initial sounds of words like 'then' and 'thin'. In British English, these consonants are more likely to be dental [ð, θ].

An interdental [l̟] occurs in some varieties of Italian, and may also occur in some varieties of English, though the distribution and usage of interdental [l̟] in English are not clear.

Interdental approximants are found in about a dozen Philippine languages, including Kagayanen (Manobo branch), Karaga Mandaya (Mansakan branch), Kalagan (Mansakan branch), Southern Catanduanes Bicolano, and several varieties of Kalinga.

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