Hey SMarioCh,
I've sort of experienced this issue before, then it went away, so I'll try my best here. Go to Sound in the Control Panel or right-click the Sound icon on the bottom right, then click Sounds, and go to the Playback tab in the new window.
You'll then have to go to your primary playback device, double-click it and go into the Advanced tab, and uncheck "Allow applications to take exclusive control of this device".
What's going on here seems to be noise suppression, I'm not sure what would be causing it, but hope this helps, let me know of the results.