According to Nielsen//NetRatings, two-thirds of all Americans use their mobile phones while in the bathroom. Sun Microsystems has come up with a way to detect when a cell phone is in use in the bathroom in order to provide bathroom-specific mobile advertising.

“When you’re in the bathroom, you notice the slight echo. Sound echoes of the tile… that’s also what makes the bathroom a great place for singing. We’ve put together a piece of software that will detect the echo-frequency range present in most bathrooms through a mobile phone’s microphone,” says Sun researcher Torri Niemczyck. “That way advertisers can detect when mobile users are in the bathroom, and serve them ads for things like hand soap, dental care, and even beauty products.”

The Sun software works on any java-enabled mobile phone with an internet connection. Sun Microsystems says they are already talking to Opera about inserting the bathroom-targeting technology into the upcoming version of Opera’s mobile web browser. Opera is currently offering their Opera Mini mobile browser as a free download. Sun’s technology could open up a new source of revenue for them, alongside of Google search referrals.