A storm drum, often referred to as a thunder drum or thunder tube, is a percussion instrument that produces a sound similar to rolling thunder. It typically consists of a cylinder with a drumhead on one end and a spring attached to the center of the drumhead. When the spring is shaken or struck, it creates vibrations that resonate through the drum, mimicking the sound of thunder. This instrument is commonly used in theatrical productions, sound effects, and ambient music to evoke the feeling of a storm.