Generating electricity from sound waves

I found this kind of interesting: http://www.pcworld.com/article/227410/Coming_Soon_Yell_At_Your_Phone_To_Charge_It.html#tk.rss_news

I've also seen stories in the past about picking up the energy from WIFI to charge mobile devices. Thinking about it, if the physical components to do this we manufactured small enough, you could have the infrastructure to charge from stray electrical current, sound and even solar all built into one device. I wonder how long it will be until our devices no longer need to be plugged in at all?

This probably explains why I feel drained after shouting at the kids.

Perhaps some bright spark could create a device to capture all of the hot air spouted about the cloud, that could stop climate change, ease world poverty, and end discrimination.

Hmm... you think it could do the last two as well? LOL!

That amount of energy - no problem.

really?