登闻鼓, the drum that reaches the ruler’s ears, was a drum hung outside the palace gate. Subjects could beat it to bring a grievance or a remonstrance to the emperor. The dictionary cites a passage from the Book of Jin in which people beat it.
The Ming dynasty county office of Pingyao also had such a drum. Commoners could beat the drum to state a grievance. Disputes over marriage, land and fights, however, first went to village mediation. Only when mediation failed could a person file a complaint and beat the drum.