Read the following article and answer the question.

He basically went into training , studying with a good friend who did make the line and then with an accomplished quad teacher . ( I still have n't figured out why they are called quads when there are five drums on the rig . ) He practiced while awake and in his sleep . He used his fingers to practice while sitting at the kitchen counter or while stopped at traffic lights ; he used chopsticks waiting for meals at Chinese restaurants , wooden spoons while making chocolate chip cookies , well , you get the picture . I am very happy to report that his dedication and hard work paid off .

Why is the subject banging so much ?
They are practicing drums .