<http://schema.org/about>
"I am not certain this would work: \"Without the use of external power or batteries, the Phonofone inventively exploits the virtues of horn acoustics to boost the audio output of standard earphones to up to 55 decibels which is roughly the maximum volume"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/culture/amplify-your-ipod-without-batteries.html>