From the Manufacturer

Add digital sound to your LGB locomotive. This advance unit includes electronics, a volume control and a speaker all in one compact unit. It's small enough to fit easily into most LGB freight and passenger cars or in the cab of many LGB locomotives. Just connect two wires to track power or to loco multi-purpose socket and you're ready to enjoy digital sound. This unit offers authentic diesel sound. With the LGB Multi-Train System (MTS) you can operate bell, whistle, brake sounds and conductor announcement. Best of all it's engineered for easy do-it-yourself installation.