Your speakers may sound muffled due to a setting in the audio settings. To change this, tap and hold your finger on the speaker icon on the task bar. Click "Playback Devices" in the menu that appears. In the playback devices menu, tap and hold on "speakers" and then select "properties". Tap on the "advanced" tab in the properties menu. Next, tap on "default format" and select a higher quality audio setting form the drop-down menu. Click "Apply" and see if your speakers sound any better.