Handsfree shells

Today, while driving home, i saw someone talking on their mobile whilst driving.

Surprisingly enough... it got my mind wandering...

Talking on your mobile must be illegal because you don't have both hands on the wheel. It can't be because you are distracted by the conversation, or you couldn't use handsfree sets or converse to passengers.

If this is the reason, then would putting a shell to your ear and listening to "the sound of the ocean" be illegeal whist driving as well???