Headaches, nausea, dizziness, and confusion are among the most common symptoms of a concussion. But researchers say a blow to the head can also make it hard to understand speech in a noisy room. Emily Kwong chats with science correspondent Jon Hamilton about concussions and how understanding its effects on our perception of sound might help improve treatment.For more of Jon's reporting, check out "After a concussion, the brain may no longer make sense of sounds."You can follow Emilly on Twitter @EmilyKwong1234 and Jon @NPRJonHamilton. Email Short Wave at ShortWave@NPR.org.