LAS VEGAS — Talking to the TV is usually a sign of extreme agitation, mental instability or loneliness. LG Electronics is set to make it a more rational behavior this year, with a range of TVs that respond to speech.

The company will sell a remote with its high-end flat-panel TVs that contains a microphone. You’ll be able to speak into the microphone to enter text on the TV for Twitter updates and Web searches. You won’t be able to change the channel or control the volume by yelling at the TV.

TV makers will be showing off many variations of so-called “smart” or Web-connected TVs at this year’s International Consumer Electronics Show in Las Vegas. LG Electronics USA showed off its new TVs Monday, a day ahead of the show’s opening.

“Smart” TVs have been around for a few years, but two things are holding them back. One is that the conventional TV remote is a hopeless tool for Web browsing, typing, and other PC-like behaviors.

“Anyone who’s actually checked email on a 50-inch TV knows it’s not a good experience,” said Shawn Dubravac, head of research at the Consumer Electronics Association, which puts on the show.

As TVs have become more and more capable, that’s meant more buttons on the remotes, but that’s a trend that can’t continue, he said. TV makers are now looking around for alternatives. Last year, LG introduced a “Magic Wand” remote that’s motion-sensitive, much like a game-console controller. This year, it’s taking another page from Microsoft Corp.’s Kinect game console and introducing a 3D camera that perches on top of a TV and interprets the viewers’ motions, letting them control the cursor with hand movements.

“I think 2012 will be the year of the interface,” Dubravac said.

The other thing holding back “smart” TV is that viewers interact more with the cable or satellite set-top box than they do with the TV itself. The set-top box is where you find shows and change the channel.

Cable and satellite companies seem far less interested in revamping how people interact with their boxes. Dish Network Corp. unveiled a new box it calls the “Hopper” on Monday. It takes digital video recording to a new level by automatically recording all primetime shows of the four major networks.

But it comes with a conventional remote, covered in buttons.