The consensus seems to be that children still sing as they play (no surprise :), but that they don't sing the same songs.

There was someone who went around the US recording sounds. He/she/they had street vendors, children's play songs, buskers, people who could sing double stops, you name it. It might not have been one person, but a project--maybe even one of those depression projects.

I think the Library of Congress has the recordings now. Does anyone remember who that (they) was (were)? They were played on the radio during the 60s folk revival, so they must be available.

Murray