I'm running Win10 1903 and AORUS Master motherboard with onboard Realtek sound and the current driver. With MCE and Radar Contact running in P3DV4.5 my voice (communications) volume drops after a short time even though SOUND > COMMUNICATIONS is set to DO NOTHING.

After playing around with various settings I found that after startup if I went to SOUND > COMMUNICATIONS and ticked REDUCE THE VOLUME OF OTHER SOUNDS BY 50%, pressed APPLY, then ticked DO NOTHING and pressed APPLY again the problem didn't occur.

To keep from having to do this every time I start the system I created a batch file using notepad that I named COMM.BAT and saved it to the desktop. This does the same thing as above but uses registry commands. Then I placed it in the STARTUP FOLDER so it runs every time I start the system.

Content of the batch file is just 3 lines as follows:

REM When windows detects communications activity / 0 - Mute all other sounds / 1 - Reduce all other by 80% / 2 - Reduce all other by 50% / 3 - Do nothing
reg add "HKCU\Software\Microsoft\Multimedia\Audio" /v "UserDuckingPreference" /t REG_DWORD /d "2" /f
reg add "HKCU\Software\Microsoft\Multimedia\Audio" /v "UserDuckingPreference" /t REG_DWORD /d "3" /f

1. Right Click the batch file desktop icon and select Cut.
2. Right click Start, click Run
3. In the Run window, type shell:startup then enter to open the Startup folder.
4. Once the Startup folder is opened, right click inside the folder and select Paste to paste the file into the Startup folder.
5. Close the Startup folder and restart the system.

Hopefully this will work for anyone who has this same problem as it does for me.

Thanks for this Harry. This sound bug in windows has been really annoying. I found that your manual fix works but I couldn't get your bat file version to work. The bat file version does do the switch in the dialog box but it doesn't change the sound. Seems like it needs an actual mouse click to trigger it. Never-the-less the manual method works so thanks.