From what I understand, zeta was pronounced as /zd/ in Attic during the 5th century BC arising from a previous /dz/.
Was this metathesis unique to 5th c. BC Attic or was it innovated by other dialects of Ancient Greek?
From what I understand, zeta was pronounced as /zd/ in Attic during the 5th century BC arising from a previous /dz/.
Was this metathesis unique to 5th c. BC Attic or was it innovated by other dialects of Ancient Greek?
Per Teodorsson 1979:325
In Elean, Laconian, and temporarily in Cretan, the normal spelling is ⟨Δ(Δ)⟩, beside ⟨Τ(Τ)⟩ (Cret. and El.) and ⟨Ζ⟩ (Cret.). In these dialects, then, the pronunciation was probably [d(:)], or an affricate, or possibly [ð(:)]. The last two alternatives are also most probable for Corinthian and Argolic.
("On the Pronunciation of Ancient Greek Zeta", Sven-Tage Teodorsson, Lingua 47, 323-332)
Teodorsson interprets [d(:)] as the endpoint of a change *[ʒdʒ] > *[ʒd] > *[zd] > [d:] (page 330).
Teodorsson (at least at this point this article was written) did not accept the communis opinio that zeta became [zd] in Ionic-Attic: he considers [zd] in the historical period to have been a pecularity of the Lesbian dialect (corresponding to the transmission of the digraph spelling "σδ" in Lesbian poetry):
It appears that the occurrence of [zd] in historical Greek is reduced to literary Lesbian, and to the theory of the grammarians. It is tempting to surmise that this coincidence may be significant. It was perhaps only in Lesbian that [zd] (< *[ʒdʒ]) was not assimilated into [d:] but remained in historical times.
(330-331)
Note that the general topic is one of the most debated points of Ancient Greek phonetics. There is copious literature on it that I have not read. For a conflicting viewpoint, see Cairnarvon's answer to What evidence is there for the classical pronunciation of zeta?