PROFESSIONAL COMEDY is tough. There are thousands of would-be comics, swallowing apples or appearing on the Gong Show, but few of these people have what it takes to become a successful comedian. First, you have to be funny; second, you have to be able to maintain your comic appeal for a long time--what good is a profession that you can pursue for only a few years? Although comedian Steve Martin may not be able to long maintain his frenetic style, he is now at the top of the profession. His fans emulate his manic delivery as well as his jokes, and Steve Martinisms are now popping up in conversations all the time. With the Martin delivery, an expression like "I'm a crazy kind of guy" can quickly become a byword.

Martin has enjoyed an incredible success on television. Martin, one of the most popular guest hosts on the Tonight Show, recently broke from the traditional routine of walking on to the stage to deliver his monologue. Instead, he drove out in a small sports car, raced across the stage to say hello to that night's stand-in for Ed McMahon and then drove back across the stage to greet the band.

Much of Martin's comedy relies on sight gags, which he pulls off very well. He may walk onto the stage and claim to be a professional comedian and then proceed to knock over the microphone. Or he may display his bunny ears or an arrow stuck through his head. At a concert earlier this year at Symphony Hall, Martin wanted to give his audience their money's worth and offered to show them "something you don't see every day." At that point he began to jump up and down and scream like a depraved lunatic.

You won't see something like that on Martin's first, and so far only, record, "Let's Get Small." That's the main drawback of the album, which is very funny in places. "Let's Get Small" was recorded live during a performance at the Boarding House in San Francisco. The effect of Martin knocking over his mike is just not the same on a record as it is when you see him do it. And the faces Martin makes as he plays the banjo are very hard to imagine when you're sitting in your living room listening to the record.

Still, there are many very clever bits on "Let's Get Small," despite the problems of sight gags that the listener can only imagine. Martin's voice is magnificent and many of his jokes work because of his ability to change his speech patterns so well.

Martin uses sight gags to start a successful routine. He tells the audience that he wants to play a song on his banjo (which he plays admirably on the record) and that he needs a blue spotlight for the number. The lighting crew at the back of the auditorium doesn't respond to his request. So Martin launches into a tirade about the hippie lighting crew that thinks it knows more about show business than Martin does, even though he's been in the business "for a few years, and I think I know what works best:"

I'm sorry, but I'm angry. I come out here and Ih-can't get a little cooperation from the backstage crew?

EXCUSE ME!

I'm sorry, I'm pissed.

Much of "Let's Get Small" is very funny, but He doesn't make fun of society directly but packs his stories with non sequiturs and relates incidents that could never happen. He begins the Grandmother's Song with an innocent verse that any matriarch would be proud to hear her offspring sing:

Be courteous, kind and forgiving,

Be gentle and peaceful each day,

Be warm and human and grateful,

And have a good thing to say.

But there is a marked deterioration in the song until the last verse, when Martin tells his audience:

Be tasteless, rude and offensive,

Live in a swamp and be three-dimensional

Put a live chicken in your underwear,

Go into the closet and suck eggs.

MARTIN CONSTANTLY catches his audience off-guard. He offers a solution to the population problem--impose the death penalty for parking violations. He tells the audience what to do in uncomfortable situations. When someone asks you if you mind him smoking, simply reply, "No, mind if I fart? It's a habit I have."

Martin excels at story-telling. He strings the audience along and then delivers the devastating punch line. He tells a story about his depression:

I guess I miss my girlfriend. She's not living any more. I guess I kind of blame myself for her death. We were at a party one night and we weren't getting along-we were fighting and she began to drink and she ran out of the car and I followed her. I guess I didn't realize how much she had been drinking. She asked me to drive her home and I refused. We argued a bit further. She asked me again, 'Would you please drive me home?' I didn't want to--so I shot her. (Pause) With a shotgun. (Pause) Cut her right in half.

Much of "Let's Get Small" is very funny, but Martin could produce a much funnier album if he kept himself within the limitations of the medium. By cutting a record from a live performance that often relied on visual jokes, Martin has diminished the quality of his album.

Probably the larger question is, how long will Martin be around? Will it be possible for him to maintain the same type of absurd humor for the rest of his career? Hopefully his career will last long enough for him to make more albums that should improve as he learns what is effective in disc form.