Sound security?

A recent article at CNN describes a new computer attachment designed to control internet access. The basic idea is to use ultrasound to measure the bone density of the computer user. There are a number of companies such as Sunlight that sell ultrasound equipment for medical use to follow osteoporosis- a low bone density condition.

Presumably someone with low bone density (like a child) would not be allowed to access adult only sites. Conversely, someone with high bone density (like an adult pedaphile) wouldn't have access to a child only chat room. Unfortunately, bone density changes slowly and varies widely. I don't see this as a foolproof security tool. It seems you could defeat it with a simple fake bone (a phantom) that is widely used to calibrate bone density measurements by ultrasound. I could see a kid using a piece of chalk in a thin walled aluminum tube to defeat this thing.

Don't look for this on store shelves anytime soon.