Audio volume level increases automatically when using record function in MATLAB?

I have the Windows system volume set to 50%, but I see the volume automatically increase to around 100% when I use the record function in MATLAB. It returns back to the previous level only after I call the stop function.

% System volume is currently set to 50%
rec = audiorecorder;
record(rec); % System volume increases to close to 91%
stop(rec);   % System volume returns back to 50%

Is there a way I can prevent this from happening?

Answer 1

[MathWorks MATLAB Hardware Team]

This is due to a Windows level system setting that adjusts the volume of different sounds when you are using the microphone.

To disable this setting:

1. Go to Control Panel > Hardware and Sounds > Sound
2. Go to Communication Tab in the "Sound" dialog window and select the option "Do Nothing"
3. Click on OK