Most of the time, he's mild-mannered Barry Hansen.

Dress him up in a tuxedo and put him near a turntable, though, and he's transformed into Dr. Demento, champion of "mad music and crazy comedy." For 15 years he's been hosting "The Dr. Demento Show," a radio program syndicated to 180 stations around the country, parlaying an enormous record collection (200,000 discs) and an encyclopedic knowledge of pop music into an empire of audio zaniness. Its latest manifestation: "Dr. Demento Presents the Greatest Novelty Records of All Time," a six-record set collecting 80 of said tunes from the last 40 years under one woofer.

Since many, in fact most, of these records are hard to find in retail stores, Hansen's year-long project has about it a sense of mission. He's taken novelty records off the wall and injected them back into the mainstream.

"I'm trying to raise the profile of the genre," he says, "to give it, dare I say, some dignity. I want people to realize that this is a particular type of entertainment that has a history to it. It hasn't just popped up helter-skelter now and then. There are people who are great artists who have worked in this field."

Spike Jones, for one: the master of musical mayhem, head of the Musical Depreciation Society. Barry Hansen was just a typical 4-year-old Minnesotan (a few months older than Bob Dylan, a few months older than Garrison Keillor) when his father brought home a copy of Jones' "Cocktails for Two." That was it. From that moment, he was hooked; by age 9, he had already accumulated an impressive library.

" 'Cocktails for Two' was the biggest seller of Jones' career and he was the greatest single artist in the genre's history," Hansen enthuses. "Spike was a master of the form and I keep his memory alive on my show. He's the Babe Ruth of the novelty record." Stan Freberg, Hansen adds, "would be the Mickey Mantle" and Tom Lehrer, perhaps, the Roger Maris.

Dr. Demento's "Novelty Records" lineup includes many familiar names: Jackie Gleason ("One of These Days -- Pow!"), Arthur Godfrey ("Too Fat Polka") and Groucho Marx ("Hooray for Captain Spalding"). It also includes many less familiar ones: Julie Brown ("The Homecoming Queen's Got a Gun"), Dr. West's Medicine Show and Junk Band ("The Eggplant That Ate Chicago"), the Hoosier Hot Shots ("I Like Bananas Because They Have No Bones"), Nervous Norvus ("Transfusion").

The oldest cut on the set is the "OKeh Laughing Record" from 1922, but according to Hansen, the novelty genre dates back to the turn of the century, and begins with "the oeuvre of Cal Stewart doing Uncle Josh . . . He was a standup vaudeville comedian who made numerous records; the Uncle Josh character was a New England hayseed farmer who in many of the routines outwits the city sharpies who come to show him what's newfangled. Other routines deal with him trying to master the complexities of new inventions such as the automobile and the telephone. It's fascinating to hear something recorded in 1903, when automobiles were still a novelty."

The good Doctor's knowledge of record history is as vast as his collection. As an undergraduate at Reed College, he wrote a thesis on the operas of Wagner, Debussy and Berg; his master's thesis at UCLA was on the evolution of rock 'n' roll. He wrote for the early Rolling Stone and for several years contributed columns on vinyl ephemera to Warner Bros.' Circular and Wax Paper magazines. He also worked for a number of record companies, creating historical and thematic compilations of rock, gospel, R & B and blues.

The name change came right after his first radio show, when a listener called in to say that he must be demented to be playing such garbage.

To keep his "Novelty" package broadly appealing, Dr. Demento concentrates on post-1940s tunes. He points to the first half of the '60s as novelty music's golden era, particularly in terms of quantity and chart success. "There was a pretty consistent flow from beginning of the phonograph until the late '60s," he says, "when it started to slacken off as rock 'n' roll took itself more seriously. One of the results seemed to be that eventually even top 40 radio became less frivolous.

"As radio became more of a big-money business, run by corporations rather than by local entrepreneurs flying by the seat of their pants, they did research and they found that people grew tired of novelty songs quickly. Whereas radio stations in the '50s sought out novelty records as a way of creating a buzz on the street, nowadays radio stations seem less concerned with getting people excited and tuning in than they are about people hearing something they don't like and tuning out. They want people to just leave this thing droning in the background for as long a time as possible."

The crunch came in the mid-'60s, he says, "with Dylan and the Beatles becoming more ambitious. And then there were all the hyphenated rocks that came after -- jazz-rock, folk-rock, art-rock -- which I loved. But in the end you were less likely to hear 'Itsy Bitsy Teenie Weenie Yellow Polka Dot Bikini' on your local radio station."

Of course, it is radio -- and "The Dr. Demento Show" in particular -- that has kept the genre alive. "It grew and prospered and inspired a new crop of novelties like 'Pencil Neck Geek,' 'Dead Puppies,' 'Fish Heads' and so on. The genre had kind of gone underground and I am reversing it."

Still, Hansen says, radio today remains resistant to novelty songs "with the exception of morning men. Every city has its zany morning people -- here you have the Greaseman -- and they're often given more freedom than the other deejays. They'll often work in some zany novelty things, sometimes they even make them themselves, do their own parodies."

He is pleased by the success of current parodies like Cheech and Chong's "Born in East L.A." and the rise of new comics like Steven Wright, Emo Phillips and Weird Al Yankovic. Especially Weird Al.

Yankovic ("Another One Rides the Bus," "Eat It," "Like a Surgeon") is a Dr. Demento discovery. When he was still in high school, he sent Hansen a tape, a voice-and-accordion tribute to his car. Weird Al had his first hit -- a delicious parody of "My Sharona" titled "My Bologna" -- in 1979. He's gone on to record three albums, make numerous videos and write his very own semitrue autobiography, which he describes as "the most important book ever written in the history of mankind."

These days, Hansen gets 30 or so tapes a week over the transom. "They range from 10-year-old kids singing into a $20 tape recorder to radio deejays doing special projects in their production rooms. Nowadays, any well-off suburban kid can afford a four- or eight-track semipro tape recorder and a mixing board for a thousand bucks. Some have learned how to use them well. Other use them badly."

And, not surprisingly, they use them much differently in the '80s than they might have in earlier decades.

"People are more open minded and it's a little more difficult to shock someone," Hansen says. "I have to stay in business, so I have to please the radio executives as well as the public. Basically the seven words you can't say on network television you can't say on network radio either.

"People do tend to deal in things that might make the average listener squeamish. Like Ogden Edsl's 'Dead Puppies Aren't Much Fun,' which is probably not a record it would have occurred to Spike Jones to record, but is very typical of what's on my show now.

"When 'Dead Puppies' got popular, lots of kids and various semipro bands, perhaps thinking they'd be a little more demented than that, started sending me songs whose general premise was 'Dead Puppies Are Fun,' or 'Let's Microwave the Cat.' Sometimes I get material that's extremely off-color or loaded with four-letter words, or is demeaning to women or gays, or is racist. All kinds come in the mail."

Like the National Lampoon collections of cartoons even they wouldn't print, these songs often surface on Hansen's infrequent tours (on which he sometimes teams up with Weird Al). "I used to do college lectures, 'Songs I Can't Play on the Dr. Demento Show,' but I always felt I was playing to a smaller and more restricted audience when I did that."

Barnes & Barnes, whose "Fish Heads" is one of the show's most-requested songs, originally sent in "The Vomit Song." "We certainly couldn't have played that on the air," Hansen chuckles, "since it was put together for the general purpose of making people feel revolted and revulsed. But it was a good and funny song, and I wrote back to them."

"Fish Heads," "Dead Puppies," Fred Blassie's "Pencil Neck Geek," Napoleon XIV's "They're Coming to Take Me Away, Ha-Haaa!" and Frank Gallop's "The Life of Irving" are the five most requested songs on "The Dr. Demento Show."

Of those, only Gallop's ditty (from the album "When You're in Love the Whole World Is Jewish") is missing from the Rhino collection, though there are other notable absences. "We got about 90 percent of what we wanted. Frank Zappa's work proved to be unavailable. We wanted 'Witch Doctor' by David Seville and 'The Chipmunk Song' by the Chipmunks, and they proved unavailable. Their management didn't want them appearing on anything that wasn't specifically a children's collection."

Hansen declines to pin down his own favorites. " 'Dead Puppies' may be an audience favorite, but I can't say that when I get home from a show I immediately run to the phonograph and put it on. When I'm relaxing, I may get out my Bix Beiderbecke records or check out some new rock records. Or, now that I'm married, put on what my wife likes."

His recent marriage has spurred a little household reorganization. In case you don't know it, 200,000 records can take up a lot of rooms. Hansen's Los Angeles house, a one-story, three-bedroom affair, houses half the collection. The rest resides in what used to be a two-car garage and a 36-by-14-foot patio.

"I had records in the kitchen -- those shelves were beautiful for 45s," he says, "but when we got married, she took one look and said 'If you expect me to cook, you've got to do something about those shelves.' So we had to sacrifice the patio. We built walls around it and had the roof strengthened. That's now the 78 room."

Though he's never counted, Hansen estimates his novelty collection at around 3,000 albums and singles, including comedy records. "In the course of making this album, we decided to leave out straight stand-up comedy as a means of narrowing the field slightly, as well as reflecting the fact that my radio show is about 90 percent music."

He's now looking for a way to translate the radio show to television. "It seems like such a natural," he says. "There's videos of all the new things. Even unknown groups are doing videos along with their songs these days. Plus there's a tremendous amount of older material and we could have people perform live."

The older material exists in television kinescopes and in "soundies," films made for automatic machines that were popular in bars and taverns in the '40s. "There's a good thousand of those in existence, including a good many that are humorous, bizarre, campy or entertaining to a modern audience in one way or another."

Within the novelty genre, of course, lies the subgenre of Christmas records. "There are more novelty records about that than anything else," says Dr. Demento. "Some are masterpieces of satire, others are masterpieces of insipidity."

Come to think of it, that's a pretty good description of the genre as a whole.