TECH & YOU PODCASTMost Americans probably realize we are moving to a digital TV format called high-definition television, or HDTV, but few people are aware of its audio counterpart, HD radio. As the name implies, this format aims to deliver big improvements in quality and a wealth of new services. But as with digital television, HD radio's reality falls far short of its promise.

Like its digital cousins, XM Satellite Radio (XMSR

) and Sirius Satellite Radio (SIRI

), HD radio relies on special equipment to produce much better sound than conventional analog broadcasts. HDFM offers near-CD quality, about what you hear on XM or Sirius, and HDAM is supposed to approximate conventional FM, according to promoters. But the only digital AM stations I found offered nothing but yak. Both the AM and FM varieties are mercifully free of static and hiss, though with a weak signal the sound breaks up like a bad wireless phone call.

Unlike XM and Sirius, HD radio is free to anyone with the equipment to receive it. I tried two different systems, the high-end Polk Audio I-Sonic ($599), which can also get XM service, and the much cheaper Radio Shack (RSH

) Accurian Tabletop HD Radio ($179). Not surprisingly, the I-Sonic sounded a lot better and did a better job pulling in weak signals.

Will people spring for this costly equipment just for the superior sound? I doubt it. In the case of satellite radio, it's the programming, not the improved audio quality, that justifies spending $12.95 a month. Alas, HD radio—at least as it exists today—is largely the same vast wasteland as conventional radio, with stations offering short playlists of music in a few repetitive formats.BECAUSE DIGITAL BROADCASTING uses bandwidth much more efficiently than analog, it is possible to fit two and sometimes three channels onto the same slice of radio spectrum allocated to each station. Unfortunately, not many broadcasters are taking advantage of this opportunity. In the Washington (D.C.) area, there are 18 stations providing HD broadcasts, of which only half offered a second channel. I was happy to see that American University has found a second-channel home for the bluegrass it banished from WAMU-FM but disappointed that WETA-FM hasn't done the same for classical music.

Broadcasters, who are about to start a major ad campaign to promote HD radio, promise a variety of services in the future, including real-time title and artist information, on-demand programming, and the ability to record broadcasts automatically. But to get these features now, you have to subscribe to satellite.

Of course, HD radio faces the same bind as any new entertainment technology. It's hard to draw listeners without a lot of content and cheap players, yet without an audience no one wants to provide the content or build the radios. XM and Sirius are spending tons of their investors' money to create a market, but there's no sugar daddy for digital radio. As for digital television, it has a different kind of patron: Uncle Sam. By 2009 the government will force the transition to HDTV by shutting down analog broadcasting. HD radio has no such deadline.

That makes HD radio a tough sell. For people who like to listen on the road, units for cars are available from Panasonic, Alpine Electronics, and others. But these systems are expensive and typically include satellite radio as well. Right now, only bmw pre-installs HD radios in its new cars.

So why do broadcasters even bother with digital radio? Because they need some way to compete with both satellite radio and digital music players such as the iPod, which get easier and easier to plug into home and car stereos. HD's main selling point is that it's free, but that's offset by the high cost of the radios. The real problem, however, is content. Somewhat better-sounding junk is still junk. The key for the broadcasters is content, not technology.For past columns and online-only reviews, go to Technology & You at businessweek.com/go/techmaven/ By Stephen H. Wildstrom