The storm vortex ambient sound remains after removal/destruction.
In trying to replicate the issue I cannot get it to loop more than one sound source at a time yet both on this level and others I've had countless. Makes me think its time-based, as in the previous sound-source gets overridden if a new one is created within a certain time frame. Not sure exactly what that time-frame is.
Steps to replicate:
Build Storm Vortex.
Activate and deactivate it if ambient sound does not start.
Sell it and sound continues to play, even if you leave the area and return.
While its normally not an issue, it can become very annoying on certain levels if using a turtling-strategy or where multiple turrets gets destroyed and replaced. Restarting the game or reloading save removes the ghost sources, so that is always an option in SP.
Customer support service by UserEcho