sounding-board
n
(a) board or canopy placed over a platform, stage, etc to direct the speaker's voice towards the audience, so enabling him to be heard more clearly 增音板(裝在講臺、 舞臺等上方增加音響洪亮度的板或頂篷).
(b) means of causing an opinion, a plan, etc to be widely heard 宣揚(yáng)意見、 計(jì)畫等的手段
The magazine became a sounding-board for its editor's political beliefs. 那雜志成了編輯宣揚(yáng)其政治主張的傳聲筒.