Maybe I'm biased, but I think the sound of a movie or TV program has as much or more impact on your viewing experience than the picture does.

Imagine how uninteresting "Star Wars" would be without the swishing and "wonnnnk" sounds of clashing light sabers. Or the lack of suspense in "Jaws" without the music.

Even those of us who are visual thinkers can hum the old TV theme songs of "The Andy Griffith Show," "Laverne & Shirley" or "Dragnet" -- but nobody remembers exactly what the Dragnet badge looks like, or the Shotz brewery where Laverne and Shirley work, even though the images are on screen while we hear the theme. Sound is everything!

Yet, when we buy a TV, we compare visual features first: How big is the screen? Does it have picture-in-picture capabilities? Does it hang on the wall? Sound gets second priority. I guess I'm to blame, too. When I recently reviewed an HDTV set, I too concentrated on the visuals.

The other day, though, I had the pleasure of an informal discussion with Craig Eggers, the senior manager of consumer electronics marketing for Dolby Labs, the company that pioneered noise reduction in electronic entertainment. He put it into perspective for me. You can watch video, but "to be immersed, it takes audio," he said. He reminded me that audio makes you part of the picture -- a participant.

In today's standard, that means surround sound -- something that is often referred to as 5.1. That means one channel for low frequency noises (the .1) and five discrete audio channels (two each for the left and right in front and back and one for the center, which is the one from which you get 60 percent of the dialogue).

I know what you're thinking: "Is David describing MP3?" No. MP3 doesn't mean 5.1 surround sound. It's simply a technology that compresses audio to save disk space and transfer across networks faster -- although somebody is working on a surround version of MP3.

The big value of surround is in combining video and audio. About 50 TV programs are transmitting Dolby Digital 5.1, which is Dolby's proprietary technology. Close your eyes and think of which shows elevate your adrenaline. They're probably on the list. "Lost" on ABC, a show with millions of fans; the late night shows; even MTV broadcasts with the technology. Early adopters notice the on-screen reference at the beginning of shows, but most of us aren't even aware it's there. We just know we like the show.

The Olympics, the NFL and the Grammy Awards use it -- and they all have hard-core followers. Could there be a link between the sound and the attraction? Mr. Eggers suggested to me that with NASCAR on Fox, you can close your eyes and feel the action due to the audio.

According to Mr. Eggers, even pop sensation "American Idol" features the enhanced sound technology -- although the graphic touting HDTV doesn't mention Dolby Surround Sound when it appears at the beginning of the show. That's the part that bothers Mr. Eggers -- that even though enhanced sound is an integral part of the home entertainment experience many consumers will miss out because they have limited funds and won't know enough to make sure that it's part of the HDTV sets they buy.

That would be unfortunate.