Wake up sleeping student and get sued?

Apparently parents of a high school student are considering just that after a teacher woke up a student by slapping her hand on the student’s desk.  According to their claim he suffered hearing loss as his ear was on the desk at the time and the sudden sound ruptured his eardrum.  If this is true, then I fully understand the parents’ concern, but something doesn’t seem quite right here.  From the article:

Barry said the boy’s ear hurt instantly after Nadeau hit his desk.

“He woke up and immediately felt pain in his ear,” Barry said. “I think he was so taken aback that he didn’t say anything at the time.”

The next day, Vinicios’ parents took him to the hospital after he complained of hearing loss and they discovered a bloody fluid on his pillow.

If his eardrum burst as they say, wouldn’t he have been in so much pain he would have said something?  Screamed out in pain?  Immediately gone to the nurse? I just don’t know…

Sleepy Student Claims Teacher’s Wake-Up Slam Caused Hearing Loss