Hearing loss affects two-thirds of people over age 70 and is the single largest modifiable risk factor for dementia and other health problems later in life. Frank Lin, director of the Cochlear Center for Hearing & Public Health at Johns Hopkins, talks with Stephanie Desmon about the links between hearing loss and dementia, why the new approval means hearing aids will be better, cheaper, and far more available, and how to find your own “hearing number.”