Most audio signals are passed around on cables with two wires: one for the voltage that represents the audio vibrations, and one for ground. This arrangement is often referred to as unbalanced audio.
Balanced audio, by contrast, uses three wires: one for the signal, one for the inverse of the signal, and one for ground. The balanced system helps reject noise that might appear along the length of a cable, as outside noise would be the same on both the normal and inverted wires. When these get to their destination, the inverted wire is inverted again and added together with the original signal wire, effectively cancelling out the induced noise.« Back to Glossary Index