Most of the users get frustrated when their computer screen is locked and they keep getting notifications. In order to mute the media audio in the lock screen, the screen lock has to be opened.
The best solution to this problem is the WinMute tool. This tool is available in 32-bit and 64-bit portable archives.
When you run this program, it runs in the system tray. By default, it has two settings. By default this tool mutes system audio when the workstation is locked and the screen saver is running. This tool also has many more useful options.
Click here to download this useful tool. Automatically Mute Computer Audio When Screen is Locked