Why do you allow singing during silence?
Singing in some strange way brings certain calmness to the mind. There are courses where we don’t sing and we go into deeper silence. That is in an advanced stage.
This is the beginning, where you are just keeping silence for three to four days. In the evening, it is good to have some music, so that it soothes the system. And if the music is there, the right brain activity is also stimulated. That is why we need both, some intellectual discussion, understanding and music, so that right and left side of the brain gets balanced.