Hearing Saver operates in the background to protect your ears from high volumes through bluetooth or analogue headsets. When you first install or update this app, you MUST open it at least once!
After initial setup, Hearing Saver should work without further input from you. To setup the app, open it. You will be presented with the Setup screen. It contains a number of controls, and they each interact to allow you to customize Hearing Saver's operation. They include defaults for ringer and media, plugging and unplugging or to remember last volume.