When grandpa can't hear words at a noisy holiday gathering, too many brain cells may be firing at once

Looking for answers about how the brain works amid age-related hearing loss, researchers say they found that old mice were less capable than young mice of 'turning off' certain actively firing brain cells in the midst of ambient noise. The result, they say, creates a 'fuzzy' sound stage that makes it difficult for the brain to focus on one type of sound -- such as spoken words -- and filter out surrounding 'noise.'