Definify.com
Webster 1913 Edition
Sounding-board
Sound′ing-boardˊ
,Noun.
1.
(Mus.)
A thin board which propagates the sound in a piano, in a violin, and in some other musical instruments.
2.
A board or structure placed behind or over a pulpit or rostrum to give distinctness to a speaker’s voice.
Webster 1828 Edition
Sounding-board
SOUND'ING-BOARD
,Noun.