Imagine Your: Town with the people talking, baby crying and children at play. Depot with train anouncements and the conductor calling out 'All Aboarrrrrrrrrrrd!'. Engineer talking to the tower and other railroad radio message. Factory with noises of the machinery Water tower and the sound of the steam train getting filled. Farm with sounds of livestock. Brook, river or waterfall with sounds. Sound of a train as it rubles by a focal point or pulls into a station. I did it! How To: Record or Download the sounds to your bluetooth enabled smart phone Find a suitable app to read them Link your smart phone to the speakers For multiple locations Either: Multiple phones operated by one person One phone with several sounds on it Downside: For continuous sound you need one phone and set of speakers for each location Cost: $10 to $30 per location Family would have to contribute their phones now and then. My family has 5 active phones and 3 older phones which are being tested. Currently in 'test' mode awaiting more cheap speakers but it worked great with my bluetooth ear buds. Long Term Idea Recordable sound chip with: Battery opperated speakers Optional bluetooth control Anyone able to make something like that cheap? Feedback invited. Feel free to be serious Constructively but openly critical Humorous, but be nice.
I saved an old Phillips MP3 player and a small iHome speaker to put in a building. Access to player will take a little creativity.
I'm thinking of period correct music for my "someday" passenger train. (~1940 - 1963) I have a 4-6-0 to pull it, still need 4-6 cars and a R.R. Maybe MP3 and some speakers, it's kind of a future thing but at least I have a list.
There are several modules available that you can download sounds to, some you save the sounds on an SD card and some you download through USB. . I don't know of any off hand that have bluetooth control, but they do have the ability to wire in button control, which would be easier anyway. Here are a few: https://www.dfrobot.com/product-1121.html https://www.dfrobot.com/product-2232.html https://www.adafruit.com/product/2342 https://www.adafruit.com/product/2217 https://www.adafruit.com/product/2133 https://www.sparkfun.com/products/14006 Some of them have multiple inputs that will trigger individual sounds, so you could have triggers on the layout activate sounds (i.e. crossing gate sound when a train passes a crossing, or a button to trigger water filling sound, etc.). With a little additional work many can be interfaced with an Arduino to give even more control over the sounds (such as randomly triggered sounds).