A good leader is able to figure people out and how they operate because they will be able to get the best out of their group this way. When a leader incorporates a dominant voice that breaks through others when needed, this is a powerful trait.
A leader should be able to understand his group or employees and what makes them "tick" so they are always getting maximum productivity. Having a strong voice when things get out of hand and the ability to get the rest of the group back on track is really important. Using it and abusing it are two different things how ever, you don't want to always have to be yelling at the top of your lungs to restore order in your group.