A large‐display sound‐level meter has been constructed as an experiment in public education. The indicator is an array of lights so arranged that the sound level produced by a source is displayed as an illuminated column. In a roadside installation, motorists see a thermometer‐like display ahead and can compare the level produced by their own vehicles with the maximum level permitted by legislation, as shown by vehicle silhouettes. The device registers from 70–100 dBAin 2‐dBAsteps with an accuracy approximately equal to one increment of the scale.