- 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.
- a structure over or behind and above a speaker, orchestra, etc., to reflect the sound toward the audience.
- a board used in floors, partitions, etc., for deadening sound.
- a person or persons whose reactions serve as a measure of the effectiveness of the methods, ideas, etc., put forth.
- a person or group that propagates ideas, opinions, etc.: He was more of a sounding board than a novelist.
- a thin wooden board in a piano or comprising the upper surface of a resonating chamber in a violin, cello, etc, serving to amplify the vibrations produced by the strings passing across it
- a thin screen suspended over a pulpit, stage, etc, to reflect sound towards an audience
- a person, group, experiment, etc, used to test a new idea, policy, etc, for acceptance or applicability
