Extremely loud, often with especially deep richness of sound.
Example:
Even without a microphone, his stentorian voice broadcast the message of peace to the farthest reaches of the auditorium.
Stentor, like Hector, was a warrior in the Iliad, but on the Greek side. His unusually powerful voice made him the natural choice for delivering announcements and proclamations to the assembled Greek army. One who speaks in a stentorian voice thus can be heard clearly at a considerable distance.