Age-related hearing loss, or presbycusis, affects one-third of adults over the age of 65. Conditions such as heart disease, high blood pressure and diabetes can contribute to hearing impairment as we age.

Noise-induced hearing loss results from long or repeated exposure to sounds at or above 85 decibels (about the level of noise in city traffic). An estimated 15 percent of Americans between the ages of 20 and 69 – about 26 million people – have high-frequency hearing loss that may have been caused by exposure to loud noise at work or in leisure activities.

Ear infections can affect children’s hearing temporarily. But if left untreated, chronic infections can lead to scarring and cause permanent damage. What’s more, fluid buildup in the middle ear can impair a child’s hearing at a critical time for speech and language development.

Hereditary factors cause a large percentage of hearing loss in children.

Sources: National Institute on Deafness and Other Communication Disorders, www.nidcd.nih.gov, and Center for Hearing and Communication, www.chchearing.org.