Your religious neighbour may have been wrong about the satanic messages hidden in your new-fangled rock music, but researchers at Disney have figured out a very real way to hide data within songs. In a new study, they explain how the next concert or movie you go to could broadcast content to your phone through sound.
Disney published a concept for the technology back in 2013 that focused on beaming information to smartphones during movies, and you can do something similar with tools like Coagula. But the study (PDF), presented earlier this month at a conference in Austria, gives us a little more information about how it works. It doesn't need any network infrastructure whatsoever -- no Wi-Fi, no radio frequencies. All you need to receive it is a phone.
The team tested a number of different methods of hiding data in audio tracks, including spread spectrum hiding, which "relies on pseudo-random sequences embedded as noise in the frequency domain and exploits auditory masking to hide information in audio signals." It also uses phase coding to manipulate "the phases of several subbands in the frequency domain to encode a message." Their system uses multiple smartphones in the audience to correct errors -- your phone will collaborate with your neighbours to make sure the broadcast comes through loud and clear.
Disney might be developing the tech for movie theatres and concerts, but the team clearly has its eye on far broader applications. "In many parts of the world, a dedicated network infrastructure is not practical or popular. Yet smartphones are popular and prevalent," the authors write in their conclusion.
This could be a cheap, fast and easy way to transmit information in places that have the phones, but not the network. Perhaps ultrasonic malware is a little closer than we think. [Disney Research; New Scientist]