AIRWAVES PICK UP SOUNDS OF THE '70S

The decade everyone couldn't wait to be over is back.

In stereo.

Fueled by thirtysomething nostalgia for the simpler times of the 1970s, radio is bringing back music from the era associated with bell-bottoms, big hair, and the Bradys.

All-'70s radio stations are cropping up everywhere, combining the ballads of Jim Croce, the hard rock of Led Zeppelin, and the disco ``Saturday Night Fever'' soundtrack on the same peculiar playlist.

Playing back the oldies is not new to radio, but waxing nostalgic for the '70s is a fresh approach. Executives who made the switch say they're targeting the people who listened to the music in their formative years and have just hit the age when they're old enough to miss it.

``People tend to be most attached to the music from their teens and early 20s,'' says Julian Breen, program director at WMGK-FM in Philadelphia, which went all-'70s last summer. ``There's something about that age that tends to fix a musical taste among a lot of people.''

Just over a year ago, stations in Tampa, Fla., and Los Angeles were the first to go all-'70s. Since then, stations have switched in nine of the country's 10 largest radio markets. New York is the only holdout.

A Seattle station went a step further and rehired some staff members who worked for the station in the 1970s.

``This format is going to be in every market in the country by midyear next year,'' says Greg Strassell, vice president of programming for WCGY-FM in Boston, which switched formats last September. ``Everyone has to have one.''

WMGK-FM in Philadelphia was known as an adult contemporary station, surviving on ``oversung ballads'' by Michael Bolton and Whitney Houston, Breen says, before it switched formats last July.

Now WMGK-FM shifts between genres of the period, airing folk, soul, hard rock, and disco one after the other.

The variety is a sharp departure from today's stations with fixed formats and markets, says Tom Moon, the Philadelphia Inquirer's music critic.

The new old music has given WMGK-FM 75,000 more listeners since the summer, Breen says, and an impressive improvement in the 25- to 54-age bracket.