In order to fix the issue, right-click on the sound icon from System Tray and select Playback devices. Double-click on your audio device and select the Enhancements tab. Check the Disable all sound effects box, click Apply and then OK. After that, do the same with the Speakers from the Playback tab. If it doesn't help, uninstall Dell Webcam Center using its uninstaller or Add or Remove Programs feature (Control Panel > Uninstall a program) and download and install the latest version of the software.