As many of you know, I released an MP3 audio player board a few weeks ago, Finally, the Universal MP3 Sound Board Has Arrived
At that time I alluded to a companion board that would allow you to change sound tracks based on car speed. The board has finally arrived. 
Here's the board that is installed in the boxcar in the video with the MP3 sound board.
Wheel Speed Sensor Board
Wheel Speed Sensor Board used with Universal MP3 Sound Board
Here it is, the first test of my new wheel speed sensor board used in conjunction with a multi-channel audio board in an O-scale boxcar. There are four audio clips that will be triggered at various scale speeds. Note that the sound clips are just some random factory sounds I put on the sound card, I just wanted to be able to recognize the transitions between the speed bands. As you can tell, they're not really representative of what would be appropriate sounds for this scenario. As you can tell, the sounds change as the speed increases. The speed transition points are just a SWAG as to what would work here, they are obviously changeable in the code of the microprocessor on the board.
- The first clip is played when the car is stopped.
- The second clip is played when the car is moving until it reaches 15 scale MPH.
- The third clip is played when the car is going greater than 15 scale MPH.
- The fourth clip is played when the car is going greater than 25 scale MPH.
- As the car slows down the same speed bands are recognized and the appropriate sound clip is played.
