Voiced interdental fricative - Definition and Overview

IPA - Unicode	ð
IPA - image
X-SAMPA	D
Kirshenbaum	D
Sound sample

The voiced dental fricative is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ð, and the equivalent X-SAMPA symbol is D. The voiced dental fricative occurs in English, and it is the sound denoted by the letters "th" in this and the. It is different from the "th" sound in thing and bath, which is the voiceless dental fricative. The dental 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 teeth, as they are with other dental consonants. Features of this consonant:

• Its manner of articulation is fricative, which means it is produced by constricting air flow through a narrow channel at the place of articulation, causing turbulence.
• Its place of articulation is dental which means it is articulated with the tongue on either the lower or the upper teeth, or both.
• Its phonation type is voiced, which means the vocal cords are vibrating during the articulation.
• It is an oral consonant, which means air is allowed to escape through the mouth.
• It is a central consonant, which means it is produced by allowing the airstream to flow over the middle of the tongue, rather than the sides.
• The airstream mechanism is pulmonic egressive, which means it is articulated by pushing air out of the lungs and through the vocal tract, rather than from the glottis or the mouth.

In English

In Old English, the letters þ and ð were used interchangeably for this sound and the voiceless dental fricative, but they have been dropped from modern usage in preference for the 'th' digraph. Although the same digraph is used for the voiced and voiceless forms, these sounds are not interchangeable in spoken English.

Other languages

Icelandic retains the letter ð for this sound, and Welsh uses the digraph 'dd'.

Many commonly spoken languages, such as German, French, Japanese, and Chinese, lack this sound. Native speakers of those languages sometimes have difficulty enunciating or distinguishing it, and replace it with a voiced alveolar fricative or a voiced dental plosive.