HD: If a Tree Falls & No One Hears It . . .

Chasing an audience that has migrated to iPods, Internet radio, pay satellite services and the burgeoning world of cellphone music, the AM and FM radio industry has spent the past couple of years beckoning listeners to discover the "secret stations" of HD radio.

But what is the secret? If you were to shell out somewhere between $80 and $300 for a new radio capable of receiving the digital signals that have added about 1,600 stations across the country, what would you hear?

I spent the better part of a week listening to the HD offerings on Washington stations, and came away impressed by the commitment two stations have made to the new technology but underwhelmed by the great majority of what's on HD.

First, the good news: WHUR, the ratings powerhouse that serves up R&B, Steve Harvey's comedy and Michael Baisden's talk on its regular signal at 96.3 FM, has created a real second station for HD listeners. WHUR-World is at once something new and a throwback to the station's 1970s roots, featuring a genre-busting blend of fusion jazz, neo-soul and high-end hip-hop, all hosted live by DJs who aren't afraid to share their knowledge of the music. The station also plays world music, speeches from Howard University's Rankin Chapel and news briefs focused on Africa and the Caribbean.

Public WAMU (88.5 FM) is pumping more resources into HD programming than any other station in the region, with two additional streams on top of its regular mix of news and talk. WAMU's second channel offers round-the-clock bluegrass, featuring Lee Michael Demsey and Ray Davis, DJs who spent decades on the mother station. A third channel is a repository for National Public Radio and BBC programs that no longer air on the main FM station, including NPR's "Talk of the Nation" and "Day to Day" and the BBC's "Newshour."

HD radio -- the abbreviation summons the TV term "high-definition" but actually stands for "hybrid digital" -- is a technology designed to offer clearer sound and a way to add extra signals onto existing broadcast frequencies. (On an HD radio, you turn the tuning dial one notch up from the regular FM frequency and the second channel appears.) But while there are nearly two dozen HD-only streams now broadcasting under Washington FM stations, most are automated jukebox services playing just the hits with none of the added value that distinguishes radio from its Internet competition.

While Hot 99.5 plays Soulja Boy's "Crank Dat" and Colbie Caillat's "Bubbly," its HD "New! Music" channel spins Britney Spears's "Piece of Me" and Jordin Sparks's "Tattoo" -- but the HD service is music-only. No DJs, no weather, no traffic reports. No ads, either, which is nice, but just you wait.

While BIG 100.3 offers Three Dog Night's "Joy to the World" and Peter Frampton's "Show Me the Way," the station's Oldies on HD plays "It's the Same Old Song" by the Four Tops and "Want Ads" by Honey Cone. It's a small consolation to oldies fans that BIG's discarded format of music from the 1950s and '60s has been restored on HD, but again, it's just the tunes, with none of the personalities, news and other services that radio usually provides.

Along with providing a free alternative to the broader array of music available on the pay XM and Sirius satellite services, HD's promise is to push the pendulum back from the extreme narrowing of choice that swept through radio in the 1990s. And so WASH (97.1 FM) supplements its regular light-rock format with an HD channel of nothing but love songs (The Association's "Cherish," Atlantic Starr's "Always," Chris de Burgh's "The Lady in Red").

DC101's hard rock has a new cousin called DC202, specializing in new rock, such as "Everything in Transit" by Jack's Mannequin and "Steady, as She Goes" by the Raconteurs. And while WMZQ (98.7 FM) plays current country hits, its HD channel is devoted to classic country numbers like Willie Nelson's "Luckenbach, Texas" and Rodney Crowell's "I Couldn't Leave You if I Tried."

All-news WTOP is trying something on HD that sounds more like radio. Its iChannel is a nationally syndicated service featuring unsigned bands that submit tunes via the Web and gain airplay according to how often listeners request or comment on the music. The station has live hosts, and a webcam to prove it, but the station is coy about where it's based and has no local content. WTOP also has a useful third channel that plays the main station's traffic and weather reports on an endless loop.

But for all the hype about HD, are people listening? Even after the biggest ad campaign anywhere on radio -- with more ad spots than Geico, Budweiser or General Motors last year -- the answer is not many, according to the latest estimates.