Abstract: A sound level indicating device specifically designed for use by educators to use in teaching students the art of self-discipline when students are arranged in large groups in a large area with means for: (1) detecting noise; (2) distinguishing between noises of different decibel levels; (3) distinguishing between noises of different lengths of time; (4) ignoring isolated sounds of excessive decibel level which may occur in the midst of a general noise level; (5) switching a plurality of SPDT relays; (6) giving visual signals to indicate the rise and/or fall of noise levels in reference to a predetermined decibel level.