Singing in a dream often points to authenticity -- your own voice, literally and figuratively, being given room to come through. Singing confidently in front of others can reflect a readiness to be heard, while losing your voice mid-song often names a fear that what you have to say won't land the way you want.
The Moon is in conflict with those who are ruled by Mars, and Mars is in conflict with those ruled by the Moon. - Picatrix (Andalusia, ~1000.AD)