Open the software mixer or volume control. There are several inputs that can create noise in the speakers. The microphone and the modem are the usual culprits. Mute these two items. This should eliminate all or most of the noise.

The microphone does not have to be un-muted to use it. Un-muting the microphone allows you to hear what you are recording through the speakers. It does not stop you from recording. Therefore, the microphone should always be muted so that it does not cause the speakers to hiss or hum.

Name: Hiss or low-level hum from speakers.png Views: 137 Size: 16.9 KB

Another possible reason for sound distortion or hiss could be damaged or twisted speaker cables. Damaged cables greatly affect sound quality, causing hiss and distortion. Interference from other improperly shielded cables might also affect the quality of sound output. So make sure that all the cable and wires are in good condition, without any kinks or twists .