Six years ago, Suskind noticed a disturbing trend among her patients at the University of Chicago Medicine: While children from affluent families were starting to speak after implant surgery, those from low-income families lagged behind.Why? The question ate at Suskind, who co-founded the hospital’s cochlear implant unit in 2006. She believes she discovered her answer in research by child psychologists Betty Hart and Todd R. Risley. Their landmark study in the 1990s found that a child born into poverty hears 30 million fewer words by age 3 than a child born to well-off parents, creating a gap in literacy preparation that has implications for a lifetime.

via Children’s language development: Talk and listen to them from birth..