Acoustic vessels

brazen tubes or vessels, shaped like a bell, used in ancient theaters to propel the voices of the actors, so as to render them audible to a great distance.
See under Acoustic.

See also: Acoustic, Vessel

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
"The seismic survey vessels, the acoustic vessels and the vessels operating the ROVs [remote-operated vehicles] will stay as long as possible," said Adm Allen.