AutoPause for Firefox can pause audio and video sources if audio is playing from the active tab with automatic resume.
There are no settings, configurations, or user input to speak of other than allowing auto-updates and the ability to allow Running in Private Windows or not. Everything else is automatic. You do not even get an icon to click. AutoPause runs in the background. Even getting a screenshot during testing to illustrate the add-on working was difficult. In the screenshot, we played some tunes on Internet Radio and brought up the Tweaking.com Windows Repair Tutorial; AutoPause immediately stopped the internet Radio audio stream leaving only the Windows Repair audio output.
AutoPause will be a useful add-on for users the often have multiple tabs open that contain audio but do not want that audio interfering with the audio from the current live tab.
Similar: How-to Mute Tabs in Google Chrome, Mozilla Firefox, and Microsoft Edge Restore Accidentally Closed Browser Tabs