Quiet inside of your car

Invert (opposite phase) the sound taken from microphone and output it to speaker. It's a simple noise canceling app. Since it is made with the minimum program, if you have a smartphone with high processing speed, you might be able to keep quiet inside of your car or your room. ※For smartphones with battery saving mode, 　Auto-startup and background services may not work correctly. 　In that case, Please allow it yourself from the individual app settings on the system settings menu.