How many words does a person hear in a day?

I heard this story on NPR about the importance of having parents talk to and read to their children. What they say makes sense, but I wonder about that claim that, by the time they are 3, children from poorer families hear 30 million fewer words than children from more affluent families.

30 million is a big number. If we divide it by 3 years times 365 days per year, that works out to over 27,000 words per day. If we figure that a person speaks about 100 words per minute, that works out to 4½ hours extra hours of conversation per day. Can that be right?