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, . 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.