The voiced alveolar fricatives are consonantal sounds. The symbol in the International Phonetic Alphabet that represents these sounds depends on whether a sibilant or non-sibilant fricative is being described.
The voiced alveolar sibilant is common across European languages, but is relatively uncommon cross-linguistically compared to the voiceless variant. Only about 28% of the world's languages contain a voiced dental or alveolar sibilant. Moreover, 85% of the languages with some form of [z] are languages of Europe, Africa, or Western Asia.
The voiced alveolar non-sibilant fricative is a consonantal sound. As the International Phonetic Alphabet does not have separate symbols for the alveolar consonants (the same symbol is used for all coronal places of articulation that aren't palatalized), it can represent this sound as in a number of ways including ⟨ð̠⟩ or ⟨ð͇⟩ (retracted or alveolarized [ð], respectively), ⟨ɹ̝⟩ (constricted [ɹ]), or ⟨d̞⟩ (lowered [d]).
