Making ordinary objects into speakers isn''t a new concept. Devices that provide similar capabilities have existed for years, but those are mostly novelties with no real purpose.
A typical loudspeaker employs electric current that has been passed through a wire to form a magnetic field. This creates a speaker membrane, which then moves the air around it to create the sounds we hear.
Most thin-film loudspeakers are freestanding because the film requires space to move to produce sound. Mounting a traditional speaker onto a surface might impede vibration and limit its ability to generate sound.
The researchers developed a medium that uses tiny domes measuring 15 microns high (about one-sixth the thickness of a human hair) on a thin layer of piezoelectric material, each of which vibrates individually. Spacer layers provide enough clearance to allow them to vibrate freely, while also protecting them from everyday harm and abrasion, boosting durability.
The composition of MIT is paper thin and can be scaled up to produce loudspeakers large enough to cover the inside of a vehicle or even wallpaper a room. For example, research believes it might be used to generate sound of the same amplitude but opposite phase to cancel the undesirable sound. In other words, active noise canceling.
"We have the ability to precisely generate mechanical motion of air by activating a physical surface that is scalable," said Vladimir Bulovic, the senior author of a paper on this topic. "The possibilities of how to utilize this technology are endless."