{The seven thunders} (hai hepta brontai). A recognized
group, but not explained here, perhaps John assuming them to be
known. For rontai see already  4:5  6:1  8:5 . In  Ps 29  the
Lord speaks in the sevenfold voice of the thunderstorm upon the
sea. {Their voices} (	as heaut(936e) ph(936e)as). Cognate accusative
with elal(8873)an and heaut(936e) (reflexive) means "their own." In
 Joh 12:28  the voice of the Father to Christ was thought by some
to be thunder.