How TEEC EFLs Work

Who needs headphones when your hoodie has integrated speakers? With EFL technology, you might be able to ditch your earbuds.
Who needs headphones when your hoodie has integrated speakers? With EFL technology, you might be able to ditch your earbuds.
Courtesy TEEC

In the not-too-distant future, you may be riding the subway and find yourself overwhelmed by a blast of Lady Gaga. But "Poker Face" isn't blaring through the subway's PA system: It's coming from a tweenager's baggy pants. No, not a clip-on MP3 player -- the pants themselves are what's causing the racket. And you may have to ask him politely, "Please, please ... turn down your jeans."

Whether the idea frightens or excites you, speakers really will be integrated into clothes. And it won't stop there. You'll hear The Roots thumping from hoodies and The Grateful Dead wafting from backpacks everywhere. Maybe someone will even make a cowboy hat that plays George Strait.


It's all thanks to speakers like those from Taiwan Electrets Electronics Corporation (TEEC), which demonstrated its Electrets-Electrostatic Flexible Loudspeakers (EFLs) at the 2012 CES (Consumer Electronics Show) in Las Vegas. EFLs are thin and flexible so that manufacturers can integrate into all sorts of funky and functional products: tablet PC and iPad carrying cases, pillows, standalone portable speakers, artwork and much, much more.

For example, a sweatshirt might feature a hood with a sewn-in speaker that wraps all the way around your head. In one pocket you'd have a receiver, and in the other, an MP3 player with Bluetooth. Hit play and your music zips wirelessly from your music player to the receiver, which sends its signal to your speakers, and suddenly, your hoodie is a portable amphitheater.

EFLs are extremely svelte, with a thickness of only a few millimeters, depending on the final product's needs. They're also flexible, so you can bend them repeatedly without worrying about damage. And they're so lightweight that you won't notice them adding heft to your backpack. Just as important, they are seriously low power devices, requiring only 0.1 W, or 90 percent less power than traditional portable speakers. That means you won't need to strap a car battery to your pack to power your hoodie's musical awesomeness.

You can't waltz into an electronics store and buy these EFLs off the shelf; TEEC works only with product manufacturers. Together, the companies partner on product design and engineering so that the speaker will offer maximum benefit with minimum hassle.

From pillows to pants, there's no product that's safe now from the ubiquitous digital music revolution. Keep reading to see just how these floppy speakers work.

Electrostatic for the People

It’s not just artwork. This frame has mono speakers built in, meaning you can hang your speakers just like you would a picture of grandma.
It’s not just artwork. This frame has mono speakers built in, meaning you can hang your speakers just like you would a picture of grandma.
Courtesy TEEC

Traditional speakers are typically bulky contraptions with components like magnets, coils and cones. If you're not familiar with basic speaker technology, check out How Speakers Work. You'll see that speakers make sound by vibrating the air in front of a diaphragm to create sound waves, which our ears can hear.

A speaker's diaphragm size varies depending on the kind of sound you want to create. Big, boxy subwoofers feature diaphragms that might be a foot or more in diameter in order to reproduce low bass frequencies. Tiny tweeter speakers, on the other hand, might only be a few centimeters in diameter, which gives them a faster response time that's great for making high-pitched, high-frequency sounds.


Small or large, these rigid, relatively chunky speakers might be fantastic built into the side panels of your car. But there's no way they're suitable for, well, a sweat suit. To that end, TEEC tapped a different kind of speaker tech – electrostatic. You can read more about electrostatic speakers in Do those tall skinny speakers work differently than regular speakers?

Electrostatic speakers are nifty devices in their own right. They're a speaker sandwich of sorts, with an ultra-thin diaphragm bookended by electrically conductive metal grids, also called stators, which give the speakers a robust, sturdy structure. Tiny spacers leave just a bit of air between the diaphragm and the stators.

The stators receive alternating positive and negative charges that correspond to audio input, which in this case is the music signal. This alternating charge happens very quickly, and as it occurs, the highly charged diaphragm moves from side to side, just like a magnet that's attracted to its opposite. The wiggling diaphragm, of course, moves air and creates pressure waves we can hear.

Electrostatic speakers often contain diaphragms made of inflexible graphite. And because of the high voltage in the stators, proper distance must be maintained between all components; otherwise, you'll see a gorgeous (but highly dangerous) pyrotechnics display in your living room.

To make flexible (and non-fiery) speakers, TEEC borrowed some concepts of electrostatic speakers and added, well, their own twist.

All Set for Electrets

These portable EFLs are slim and consume very little power, so they’re perfect for long trips.
These portable EFLs are slim and consume very little power, so they’re perfect for long trips.
Courtesy TEEC

Flexibility in a speaker is a novelty. In TEEC's EFLs, it all starts with that innovative plastic diaphragm, which can wobble and bend to no ill effect.

EFLs have diaphragms comprised of transparent, thin plastic (specifically, a type of fluoropolymer), which is referred to as the electret material. The word electret is a nifty blend of two common words: electricity and magnet. This so-called electret material is the secret sauce of EFLs because it maintains a semi-permanent (or static) positive electric charge, thanks in part to tiny pores (called nanopores) in the surface of the plastic.


Ultimately, this electret material has one important characteristic: Because of its inherent charge, the diaphragm doesn't need a lot of voltage to produce movement and thus, sound. Lower voltage requirements mean the stators and the diaphragm don't require the same stringent spacing demands of a traditional electrostatic speaker.

Throw in less rigid construction materials, and you wind up with floppy yet nice-sounding EFLs that are roughly 50 to 80 percent lighter than conventional speakers. Their low power requirements mean a small battery can provide enough juice for all sorts of applications that were simply not possible with speakers that suck down more electricity.

This electrifying electret technology seems tantalizing, but you might be wondering how a sandwich of metal and plastic can possibly produce quality music. TEEC is way ahead of you.

Those Are Some Loud Pants

With EFLs inside, this cushy pillow can lull you to sleep with the soothing sounds of Rage Against the Machine.
With EFLs inside, this cushy pillow can lull you to sleep with the soothing sounds of Rage Against the Machine.
Courtesy TEEC

You might be leery of the sound quality or volume potential from speakers that are as thin as a slim piece of cardboard. TEEC is the first to admit that bass quality is not this product's strong suit. For heavy bass, a speaker's diaphragm must move a significant distance, and the skinny housing of the EFLs doesn't allow for much movement. But for high- and mid-range tones, the EFLs will sound much like average headphones or earbuds.

Volume isn't a problem for the EFLs. The lowest power (0.1W) model can play audio as loud as 73 decibels (dB). A model that consumes more power (0.3W) can pump your jams at 85dB, which would be noisier than an average garbage disposal and dangerous to listen to for a prolonged length of time.


So, these TEEC creations are loud, flexible and ready for integration into a vast array of products. You'll find them sewn into hoodies, yes, but also squishy pillows and rugged backpacks. Throw your tablet PC or iPad into a speaker-laced carrying case and you'll have full-sounding audio no matter where you go.

Or you can buy wall-ready, framed artwork with the speakers built in -- hang them in your living room, and your friends will wonder where you've managed to hide your speaker system. You might even find EFLs shouting out details from a promotional movie poster or other marketing gimmickry.

The possibilities for these slim, adaptable speakers are almost unlimited. As more product manufacturers look to imbue their goods with tunes, you might find your world turning into a virtual surround sound studio. And you might very well have to ask (politely, of course) your fellow citizens to turn down their pants.

Author's Note

I hate headphones. They fall out. They fail. The cords get tangled in the most maddening way possible.

TEEC's EFLs are a refreshing step away from headphones and from conventional speaker technology in general. And EFLs are such a new concept that we can't yet be sure what the killer application for them will be. But judging from the amount of interest that TEEC is getting from partner companies, you may see lots of flexible speakers in a lot of products very soon.


Related Articles


  • Dangerous "Decibel Exposure Time Guidelines." (May 18, 2012)
  • Guttenberg, Steve. "Electrostatic Speakers: A Very Different Way to Make Sound." CNET. March 10, 2011. (May 18, 2012)
  • Industrial Noise Control. "Comparative Examples of Noise Levels." (May 18, 2012)
  • Low, Aloysius. "Verisonix Flexible Cardboard-Thin Speakers are like Magic." CNET. Jan. 12, 2012. (May 18, 2012)
  • Mai, Tuan. "Verisonix Demos its Flexible, Cardboard-Thin Speakers." Tom's Jan. 20, 2012. (May 18, 2012),news-13906.html
  • MartinLogan. "ESL 101: Electrostatic Theory." (May 18, 2012)
  • MartinLogan. "FAQ: Electrostatic Speakers." (May 18, 2012)
  • Powers, Jeffery. "Verisonix: Speakers that can be Sewn into Bags, Clothing – CES 2012." Jan. 28, 2012. (May 18, 2012)
  • Sanders Sound Systems. "How do Electrostatic Speakers Work?" (May 18, 2012)
  • Taiwan Electrets Electronics Corporation. "Clear Response, Graceful Sound!" (May 18, 2012)
  • Taiwan Electrets Electronics Corporation. "Technologies and Applications. (May 18, 2012)