Scientists from Mid Sweden University have created paper that emits recorded sound in response to a user's touch. They presented a prototype which features printed speakers and conductive inks which are sensitive to pressure:
The team envisages that the technology could be used by advertisers, and in the future, it might even be employed for product packaging.
The researcher's display model shows its possible use for marketing holiday destinations.
Mikael Gulliksson, who led the research project, told the BBC News website: "When you approach the billboard and put your hand on a postcard that shows a picture of a beach, you can hear a very brief description of that beach."
The key to the billboard's capabilities is a layer of digital paper that is embedded with electronics.
This is printed with conductive inks, which, when applied with pressure, relay information to a micro-computer that contains recorded audio files. Sound then streams out from printed speakers, which are formed from more layers of conductive inks that sit over an empty cavity to form a diaphragm.