At John's last football practice before the big game there was an injury inflicted on him.
As John was running down the field for a play another player rushed into him knocking him to the ground.
not my fault!!
Due to the way John fell, there was damage done to his temporal lobe.
Feeling nothing beside a head ache, John went home and went to sleep.
John was on the bus to school the next morning when everything appeared louder than normal. He ignored this until he heard a cry for help that seemed to come from the house that the bus passed about a mile back. He realized that his hearing was much more powerful than before, much like a super power.
John told the bus driver to stop driving and ran down the block to where he heard the cry from. John helped the woman in distress and was then known as a superhero called "Bionic Man" for his bionic hearing ever since.