In order to fix the problem, click the icon from System Tray and move the provided slide to 100:
If the issue persists, press Alt + Ctrl + Delete key combination, open Task Manager, and close all unnecessary applications (audio/video players, chat messengers) that may use your audio card. Also, perform a full system scan using your antivirus program or a utility from the database of Software Informer. If this doesn't help, it means that these are the capabilities of your speakers. You should purchase the new ones.