Liddell-Scott-Jones

ἰσχνόφωνος (ischnophōnos) weak voiced ^G:A

ἰσχνόφωνος-φωνος, ον,

thin-voiced, weak-voiced, [Refs 1st c.BC+]; of Isocrates, [Refs 1st c.AD+]; of partridges, [Refs 3rd c.BC+]; but,

__II having an impediment in one's speech (connected by the Greeks with ἴσχω), οἱ ἰ... ἴσχονται τοῦ φωνεῖν [LXX+5th c.BC+]; also of metals, etc., χρυσὸς καὶ λίθος ὑπὸ πληρότητος ἰ. καὶ δυσηχῆ [Refs 1st c.AD+] adverb -φώνως Zos.Alch.p.108B.

_{LSJ Scripture Refs: LXX.Exod.4.10}