The manipulations that will follow are valid in the "Reading" tab (what you hear) as well as in the "Recording" tab (your microphone).
First make sure that the device used is the default one, left-click on the desired device, the "Default" button must be grayed out and a green tick will appear on the device concerned, if it is not If so, click "Default".
In front of each peripheral, you will see appear a green graduation according to the sound heard or emitted by this one.