Er, we don't want to sensationalize this or anything, but your phone could soon be at the mercy of inaudible sound pulses that trigger location-specific ads, sales promotions and other potentially demonic notifications. Unlike normal advertising within apps, and also different to sound-responsive apps like Shazam and Shopkick, a new platform called Sonic Notify is meant to work discreetly in the background, without the need for any user activation. Its creators, NY-based digital agency Densebrain, plan to attach small high-frequency sound-emitting beacons to store shelves, which will "set people's phones off" when they stand in front of a particular product. It's not clear how the platform might affect your battery life, or why you wouldn't just disable it at the first inopportune alert, but drug stores, TV networks and big players like Proctor & Gamble are nevertheless said to be gripped by the concept.