Ow ow ow. Decibel's fist. Decibel's face. But he's not going to let a silly thing like a concussion stop him! Superheroes shrug off things like those and so does our probably not certified Doctor!
He hops to his feet. "Justice never ceases!" And claps his hands together for a sonic boom attack at the ghost. Though it's weaker than usual, if the shaking and holding of that injured hand after the fact is any indication.