A study by a team of scientists from Penn, MIT, and Harvard that found that the actual quantity of words a child hears over time may not be as important as the “amount of back-and-forth conversation between children and adults” when it comes to brain and language development is highlighted.
http://hechingerreport.org/why-talking-and-listening-to-your-child-could-be-key-to-brain-development/ The Hechinger Report