This decoder is not supplied with a speaker as the model comes pre fitted Below is a list of the Function keys and their assignments applicable to this model. F0. Lights on/off F1. Sound on/off F2. Horn 1 double F3. Horn 2 double F4. Horn 3 single F5. Buffer up F6. Coupling up F7. Flange squeal F7. Carriage door slam F8. Buffer clash on wagons F9. Shunting mode. Press once and the loco moves slowly, press it again and you are back to normal control F10. Acceleration/Brake override. This function overrides the normal acceleration and braking settings. F11. Aux 1 F12. Aux 2