Question

ð English the, these, other. Note that English th can also spell the voiced version of this sound [θ], as in bath, thin, ether. In Spanish this is the normal sound the d has, unless it comes at the beginning of an utterance (after pause), or after a nasal or l consonant (ando, caldo).

Accepted Answer

Voiced Dental Fricative http://en.wikipedia.org/wiki/Voiced_dental_fricative

Symbol	ð
Name	Voiced Dental Fricative
Notes	English the, these, other. Note that English th can also spell the voiced version of this sound [θ], as in bath, thin, ether. In Spanish this is the normal sound the d has, unless it comes at the beginning of an utterance (after pause), or after a nasal or l consonant (ando, caldo).
Ref	http://en.wikipedia.org/wiki/Voiced_dental_fricative

D Voiced Dental Fricative English O Er Sound