When you say download appropriate sounds from internet do you mean with an app? I had this idea and could not find an app with great sounds that was easy to use. So where do you get these sounds from and how do you trigger them with your phone? ThanksEasiest solution for sound:
1. Get a portable bluetooth speaker with built in rechargeable battery.
2. Pair with your smartphone.
3. Download appropriate sounds from internet.
4. Run trains and control sound from phone
You can even move speaker among locomotives as and when wishes.