Katie Couric's Notebook: Quiet Cars

For decades now, automakers have been driving their engineers hard to find ways to produce quieter cars. So, why would Congress make them shift into reverse?

Blame the popularity of hybrids and those new electric cars about to hit the streets. They help cut down on air pollution - and it turns out - noise pollution too and that's the problem. They're so quiet at low speeds that pedestrians sometimes can't hear them coming doubling the risk of an accident.

A bill now being considered would force carmakers to add artificial noise to these vehicles. Nissan is experimenting with a whirring sound and a bell for its electric Leaf. GM is looking at a subtle "chirp" for the Chevy Volt.

Some people object, saying it would only add to the din of city streets. But it may be a necessary speed bump ... to make sure those fuel-efficient cars aren't just better for the air...but also safer down on the ground.

That's a page from my notebook.

I'm Katie Couric, CBS News.