If you use someone as a sounding board, you discuss your ideas with them in order to get another opinion. He needed a sounding board rather than thinking alone. someone you discuss your ideas with in order to see if they think your ideas are good sounding board for
(music) resonator consisting of a thin board whose vibrations reinforce the sound of the instrument a person whose reactions to something serve as an indication of its acceptability; "I would use newspapermen as a sounding board for such policies