Busch Comprehensive Sound Unit - "Edge of the forest"
This is the unit they use in museum displays
Realistic electronically produced railway atmosphere sound effects, triggered either automatically by passing trains or by manually by hand.
The Busch Realistic Sound Modules produce remarkably realistic sound effects (using either digitally produced sound effects or original recordings). The sound effects can be triggered using manual buttons, switches, relays or magnetic impulse switches. The speakers (included) are designed to be placed anywhere on the track. The system is designed for all scales and train set systems. System requirements: 10-16 volt power supply, AC or DC current.