Question

d͡z Sounds like English adze, but in English this is a combination of two sounds: [dz]. Old Spanish used to have this sound, written z: hazer, . Eventually, about 300 years ago it became first [ʦ] and then [θ] in northern Spain and [s] in parts of southern Spain and in all of the the Americas.  It's typically written without the ligature on top and as a single unit symbol: [ʣ].

Accepted Answer

Voiced Aveolar Affricate http://en.wikipedia.org/wiki/Voiced_alveolar_affricate

Symbol	d͡z
Name	Voiced Aveolar Affricate
Notes	Sounds like English adze, but in English this is a combination of two sounds: [dz]. Old Spanish used to have this sound, written z: hazer, . Eventually, about 300 years ago it became first [ʦ] and then [θ] in northern Spain and [s] in parts of southern Spain and in all of the the Americas. It's typically written without the ligature on top and as a single unit symbol: [ʣ].
Ref	http://en.wikipedia.org/wiki/Voiced_alveolar_affricate

English Written Z Spain D͡z Voiced Aveolar Affricate