Up close this new thin speaker is dotted with rows of sound-producing micro-domes protected by a plastic sheet. (Felice Frankel/MIT)
Have you ever had a greeting card 'sing' to you? Or a digital watch 'beep' at you?
If so, you've probably encountered a piezoelectric (say PEE-zoh-EE-lek-trik) speaker. These devices are able to produce loud sound despite being very thin and lightweight. But these little speakers have their limitations.
For one, they can only produce higher frequency sounds—these are sounds that you would maybe describe of as 'shrill'. Also, they produce sound by vibrate their entire surface area, so they can't be mounted flat against the surface of a wall. Being mounted flat would prevent them from vibrating.
That's what makes a new invention from engineers at the Massachusetts Institute of Technology really interesting. It is a piezoelectric speaker than is able to be mounted on a wall or other flat surface. And not only that, it is exceptionally flexible, too!
Sound domes
This buzzer is a classic piezoelectric speaker. It's entire surface vibrates to make sound. (Wikimedia Commons)
How is it so flexible? And how can it vibrate while still mounted to a wall?
Instead of making the entire surface vibrate, the engineers have a thin sheet of material that has a series of tiny micro-domes that do the vibrating. These domes are then sandwiched between two sheets of flexible plastic that have a series of pinholes in them to 'protect' those micro-domes.
Basically, the hundreds of domes are able vibrate inside these holes while still being securely mounted. They'll even still make sound if you bend the sheet.
What can you use this for?
That is a good question. So far, the researchers at MIT have tested a prototype that measures 10 cm by 10 cm (4 by 4 inches). But in theory, it could be made to a massive size. It could be woven into fabrics or used to line the inside of a vehicle. One of the coolest possibilities is as a sort of sonic wallpaper.
Imagine entire walls that acted like a speaker? They could also be used as a noise-cancelling surface. Noise-cancelling tech works by identifying the frequency of a sound from outside, and then quickly producing a counter, or opposite, sound that cancels it out so that you don't hear it. These kinds of speakers could turn a room into a high-tech quiet zone, free from sonic distractions!
Watch the prototype of the speaker play Queen's "We Are The Champions" below.
