I've heard of something like this. The application I heard about was for advertising purposes. eg. You walk by a soda machine and you can hear a fizzing sound, triggering you to think...."hmm, a soda 'sounds' good about now". You turn and look, and to your amazement, there's a soda machine sitting there waiting for your money! Not sure how they do it either.... probably has something to do with flux capacitors, dingle arms or gertle springs.