The other day I called a landline and heard a busy signal. And I realized that because of cell phones and call waiting, I couldn't remember the last time I'd heard one. And I grew UP with them. So imagine what it's like for today's kids.

"Mental Floss" just put out a list of 11 sounds your kids have probably never heard.

Here are some of the highlights:

--A rotary phone dial

--A typewriter

--A camera flash cube

--Changing the TV dial

--A late-night TV station sign-off

--An old-fashioned cash register

--A film projector

Do you have any to add?