Child hearing loss may indicate concussion.

In Brain Injury, Brain Science, Concussion, Senses and Perception by Brainy Days Ahead

Researchers at Northwestern University believe a blow to the head temporarily disrupts the way the brain processes and hears speech. In this study they observed differences in neural response among children who suffered concussions in the past five to 56 days compared to children without concussions. Those children with concussions had reduced reactions to the pitch of the recorded sounds. Using this information, researchers correctly identified 18 out of 20 study participants with a concussion and 19 out of 20 healthy controls. As the children recovered from their head injuries, their ability to process pitch improved.