As high-definition TVs get cheaper and bigger, many people are discovering that the joys of HDTV aren't always matched by similarly high-quality sound.

In fact, the sound from TV sets' embedded speakers has arguably gotten worse. The cathode-ray tube sets of old had plenty of room in them for high-quality speakers, whereas today's flat sets have much less space. Less space means less room for the air displacement needed to make big, beefy, well-rounded sound waves, and that means if you want good sound, you'll need to add a couple hundred bucks to your TV purchase for a nice pair of external speakers.

Now some companies say they have a better way: Transform the front of the TV screen itself into a vibrating membrane, making it in effect a giant, high-fidelity speaker, giving your HDTV an acoustic range that would make Pavarotti proud.

Emo Labs, a Waltham, Massachusetts startup, has created flat, transparent "speakers" that go in front of the display. And it is not alone in its plans to put good sound right on the face of your TV. Warwick Audio and NXT Technologies, two British companies, and a Korean firm, Plasma & Ion Beam Corp., havesimilar plans.

"People are spending a lot of money on these TVs expecting to get great video and audio," says Allan Evelyn, vice president of business development for Emo Labs. "And when they get their HDTV they are disappointed to discover their old CRT TV had much better sound."

"It's a question of physics," says Aldo Cugnini, a digital technology consultant with AGC Systems, "and physics usually dictates that the bigger speakers have higher fidelity."

Not anymore, says Emo Labs. Wheeling in at least six boxes that contained cables, a prototype 32-inch TV and a notebook computer, Jason Carlson, CEO of Emo Labs joined Evelyn in showing Wired.com an impressive demo. Every note of Diana Krall's Live in Paris coming straight from the HDTV sounded like it had been piped through a Bose speaker system. "With our flat embedded speakers the sounds come from the screen, almost like what you get in motion picture theaters," says Carlson.

Traditional speakers have three fundamental components: a cone that pushes the air, a voice coil that is an electromagnet and a permanent magnet that can attract or repel the voice coil. When the coil moves, it pushes and pulls on the cone. This, in turn, vibrates the air in front, creating sound waves.

But with thinner or smaller displays there is not enough room to create that displacement resulting in a 'tinny' and weak sound.

"Manufacturers are challenged for real estate on a display and they want it to be as thin as possible," says Cugnini. "That means they can put the speakers behind the display or at the bottom, both which are not ideal." The best sound field, say experts, comes from the spaces in front of the speaker and the screen.

For HDTV buyers, this can be a significant annoyance. HDTVs larger than 50 inches are usually connected to external speakers to create a home theater system. But smaller screens tend to be standalone, forcing users to accept poor audio as part of the package, says Evelyn.

The problem is also a result of how most consumers buy their HDTVs. Retail stores currently hook up rows of HDTVs in a bid to compare the picture quality. There's no place there to determine the sound quality on each. "Quite often the video is running on as many of these screens simultaneously and the sound isn't," says Cugnini. "And even if it is, it's not a good determination of how that audio will translate in your bedroom or living room."

Emo Labs uses a thin membrane made of polyethylene terephthalate (or PET, a plastic used in bottles) and two piezoelectric actuators. The actuators vibrate the membrane along the side, creating a force that is perpendicular to the motion. Emo Labs says it is negotiating with display manufacturers to embed its technology that users can see in TVs in the next nine months to a year.

Meanwhile, researchers at the University of Warwick hope to commercialize their flexible speaker technology by the end of the year.

Warwick Audio has created ultra-thin (0.2 mm thick) laminate panels that can be used to replace traditional magnet-and-cone speakers. Unlike Emo's, Warwick's speaker panels are not transparent. The company hopes to use them largely in public address system and displays.

The better sound quality will, however, come at price. Having a membrane in front of the display will result in about 4 percent loss in brightness, says Carlson. And then there's the additional cost that stems from making the switch to the new tech. Eventually customers will have to pay more for their enhanced audio TV sets. "Newer technologies cost more to implement so the street price of the TV will go up," says Cugnini. Emo Labs estimates its speakers would add a 10-15 percent premium to cost.

But wouldn't that be a small price to pay if Matt Giraud can sound better on American Idol, or Jack Bauer's car chases on *24 *boom just that much louder?

Top Photo: University of Warwick creates flat, flexible speaker/ University of Warwick