Speechreading with reduced vision: a problem of aging.

Presbycusis, a progressive loss of hearing in the elderly, causes people to become dependent on vision for understanding spoken language at the same time that visual disorders of aging compromise their vision. This combination of sensory losses disrupts the lives of millions of elderly Americans but remains virtually unstudied. We tested the ability of hearing and hearing-impaired adults to understand sentences spoken by an actress without sound. She was seen through various amounts of dioptric blur. Both young and elderly adults were relatively unaffected by as much as 4 D of blur. They quickly adjusted to new levels of blur, showing improved performance within a few minutes. Ocular pathologies altered the effect of blur on speechreading.