To listen is to make an effort to hear something; to be alert and ready to hear something (courtesy New Oxford American Dictionary). I especially like that last line: to be alert and ready.
Listening is an active engagement with your environment and the sound around you. It takes focus and energy. You cannot do a good job behind the mixing console without being an active listener.
Listen first. But then you need to take action and respond to what you hear.
How do you know what action to take? What are you going to do to take what you hear and make it better?