Ground loops are usually perceived as a hum or buzz in your audio signal. They generally emerge when an electrical system consisting of two or more electrical devices is connected to the electrical ground in multiple ways. If the ground of the different power sources does not have the same reference level, an equalizing current will run through the audio connection and intersperse to the audio signal.
This can also be caused by devices that introduce an electric potential to the ground connection, including peripheral devices connected to your computer. On Laptops low quality power supplies often lead to ground loop noise.
With this in mind, the following points should help to eliminate the ground loop: