Getting Too Easy To Spend My Money
"Sound could deliver the power right to the user's pocket, and so negate the need to take out the card, with the added advantage that the user could hear when their card was being powered - making life much harder for the electronic pick-pocket."
Unless the pick-pocket is using ultrasound...
Regardless, I'm not keen on the idea that people could activate my card at will, even when it is in my pocket. I'd prefer to give explicit permission for an interaction. Otherwise, why not just use facial recognition (or, voice recognition, since this is a sound-powered article) to access my account? Who needs a card?