Whitenoise does NOT automatically shut off when you exit the program. WhiteNoise will happily keep on running and running and running forever if you don't have a timer set for it. I believe this is so you can exit the program and do other things like make phone calls. However, it does mean you have to know how to shut it down manually. I can't believe that the site admin is unaware of this.
In order to shut down WhiteNoise you must hit the "MENU" button on your Android OS phone. This will bring up a pop-up menu of options - one of which is "Stop Sound". When you hit this button, WhiteNoise will stop.
Hope this helps all of you out there who are wondering why this program will not stop. :) I hope TMSoft comes up with better solution, honestly. The Iphone version of WhiteNoise has a pause button right on the main screen. This feature is desperately needed on the Android version. Frankly, I'm baffled as to why the port from the Iphone seems to be missing several key and useful features.