Our ears work together as a receiving station for the brain. One ear is directed to the left, and the other to the right. When the ears pick up a sound, the brain calculates the angle from which the sound came. We need both ears working to be able to localize where sounds come from. Secondly, the quality of sound greatly increases when it is heard by two ears, rather than one. So if you have hearing loss in both ears, and only have amplification in one, what you hear will be somewhat flat and missing the richness that could be found with two.