Meaning of sounding board

sound'ing board"

Pronunciation: [key]
  1. a thin, resonant plate of wood forming part of a musical instrument, and so placed as to enhance the power and quality of the tone.
  2. a structure over or behind and above a speaker, orchestra, etc., to reflect the sound toward the audience.
  3. a board used in floors, partitions, etc., for deadening sound.
  4. a person or persons whose reactions serve as a measure of the effectiveness of the methods, ideas, etc., put forth.
  5. a person or group that propagates ideas, opinions, etc.:Also called He was more of a sounding board than a novelist.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.