Voiced dental fricative

The voiced dental fricative is a type of consonantal sound, used in some spoken languages. It is familiar to English speakers as the th sound in father. The symbol in the International Phonetic Alphabet that represents this sound is eth, or. This was taken from the Old English letter eth, which could stand for either a voiced or unvoiced interdental non-sibilant fricative. This symbol is also sometimes used to represent the dental approximant, a similar sound not known to contrast with a dental non-sibilant fricative in any language, though that is more clearly written with the lowering diacritic, $\langle\rangle$. The dental non-sibilant fricatives are often called "interdental" because they are often produced with the tongue between the upper and lower teeth, and not just against the back of the upper teeth, as they are with other dental consonants.

This sound, and its unvoiced counterpart, are rare phonemes. The great majority of language of Europe and Asia, such as German, French, Persian, Japanese, and Mandarin, lack this sound. Native speakers of those languages in which the sound is not present often have difficulty enunciating or distinguishing it, and replace it with a voiced alveolar sibilant, a voiced dental stop or voiced alveolar stop , or a voiced labiodental fricative ; known respectively as th-alveolarization, th-stopping, and th-fronting. As for Europe, there seems to be a great arc where this sound (and or the unvoiced variant) is present. Most of mainland Europe lacks the sound. However, some "periphery" languages as Gascon, Welsh, English, Elfdalian, Northern Sami, Mari, Greek, Albanian, Sardinian, some dialects of Basque and most speakers of Spanish have this sound in their consonant inventories, as phonemes or allophones.

Within Turkic languages, Bashkir and Turkmen have both voiced and voiceless dental non-sibilant fricatives among their consonants. Among Semitic languages, they are used in Modern Standard Arabic, albeit only by some speakers, and in some dialects of Hebrew.