Anne Melson Stommel got a rude awakening one morning in 1988 and decided not to take it lying down. She had accidentally tuned her clock-radio to the raunchy Howard Stern program. And Stern's blue material made Stommel see red.

"I was outraged that the vulgarity and filth that were coming out of his mouth could be on the public airwaves that belong to you and me." said Stommel, 67, a retired technical writer who lives in New Jersey.

Stommel sent a complaint and a tape recording of a subsequent Stern show -- featuring a bawdy bit about a man who plays the piano with his penis -- to the Federal Communications Commission, which investigated. In November, the FCC levied a fine of $6,000 on three stations that aired the Stern show, including WJFK-FM in Manassas.

The FCC's actions were the latest in its effort to crack down on radio and TV broadcasters the agency deems in violation of its "indecency" standard. Like Stommel, broadcasters are upset, but for different reasons: They have long complained that the indecency regulation violates their First Amendment rights and has a chilling effect on their programming choices.

Today the issue reaches a crossroads. After a long legal battle, a federal appeals court in Washington will hear arguments in a suit challenging the constitutionality of the rule. The suit, brought in 1989 by a coalition that includes the three TV networks and the American Civil Liberties Union, also seeks to prevent the government from imposing its ban on a 24-hour-a-day basis.

Indecent material is currently banned between 6 a.m. and 8 p.m., the period in which children are most heavily represented in the audience. The FCC has argued that an all-day ban is necessary because children -- whom the standard is designed to protect -- are in the audience at all hours.

Since adopting the indecency rule at Congress's order in 1989, the FCC has cited radio stations in New York, St. Louis, Houston, Cincinnati and seven other cities, mainly for broadcasts involving sexual subjects. Another 14 cases are pending.

Yet in addition to angering broadcasters, the rule appears not to have satisfied audiences. Thousands of viewers and listeners like Stommel have written to the FCC to urge tougher enforcement, their outrage overflowing from dozens of boxes and file cabinets in two back rooms at the FCC's Washington offices. The issue has drawn more mail than any other in the agency's history.

"The critical question here is whether the government should make the decision about what children can see or hear or whether parents should make it," said Timothy Dyk, a Washington attorney who represents the group bringing the suit. "We think it's up to parents to make the choice."

The court's decision could have a broad impact on programming, according to some in the broadcast industry. If the 24-hour ban is upheld, for example, the FCC would be empowered to fine stations for material that is currently exempt from the rule because it airs in the "safe harbor" period of 8 p.m. to 6 a.m. If so, some broadcasters say this might force them to restrict the airing of risque theatrical movies or bawdy comedy shows like "Saturday Night Live."

The government's definition of indecency has grown out of a number of legal cases, most famously an action against a small New York station that broadcast comedian George Carlin's "Seven Dirty Words" routine in 1975. The government defines indecent material as "language that describes in terms patently offensive as measured by contemporary community standards ... sexual or excretory activities or organs." Speech defined as obscene is banned at all times from the airwaves.

Station executives, who can be fined up to $25,000 for each violation and risk losing their licenses for repeated indiscretions, say the indecency definition leaves too much room for selective interpretation by the FCC.

"I don't think this is an area where they can be objective. It's very muddy," said Patrick Fant, general manager of KLOL-FM in Houston, whose station was fined for a jocular "sex survey" program last year in which callers discussed oral sex, orgies and their pubic hair. Nevertheless, since being fined, the station has issued guidelines to its on-air personalities on the boundaries of acceptable language.

Other industry executives charge that the FCC is singling out radio operators for special enforcement. The FCC has cited only one TV broadcaster -- a Kansas City station that aired the movie "Private Lessons," about the seduction of a teenager by an older woman -- but that case was dropped because the movie aired during the "safe" hours. Cable programming is not covered by the indecency rule.

"Apparently, it's okay to say 'penis' on 'Geraldo' or 'Oprah Winfrey' or the 'Sally Jessy {Raphael}' show {on TV} but the way Howard Stern says 'penis' {on the radio} is not okay," said Mel Karmazin, chief executive officer of Infinity Broadcasting, whose radio stations were fined for airing Stern's program. "We are certainly interested in obeying the FCC's rules, but we need to understand them to obey them." Infinity is appealing its fines, arguing that Stern's bits were neither descriptive nor a violation of "community standards."

These distinctions appear not to carry much weight with many in the audience. Among the more than 90,000 letters the FCC has received on the subject are many from anguished parents who say their children were exposed to indecent material even when the parents were monitoring the set. A clergyman from the Los Angeles area wrote to protest a local TV station's airing of the movie "Modern Problems," during which a man is shown fondling a woman's breasts and a woman is overheard having multiple orgasms (the FCC says it can't investigate such complaints without a videotape or a transcript of "significant excerpts").

In defending the indecency ban against the charge that it is vague, FCC Chairman Alfred C. Sikes said in an interview that the commission's enforcement actions so far have provided sufficient precedent to guide broadcasters. "It's ludicrous to write down how many times someone can or cannot say the F-word," he said, adding, "It's becoming increasingly clear what the policy is."

Sikes also disputed contentions that his agency was tougher on radio programs than TV, saying that morning disc jockeys often present material "a great deal rawer" than anything on television. But Sikes added that he finds little on TV in any case that could be defined as indecent: "I have not seen anything on broadcast TV sitting at home that I would say steps over the line. But that's a narrow universe -- I don't watch that much TV."

The FCC chairman said he once sampled the Fox Broadcasting program "Married ... With Children," which has been criticized for its raunchiness, and found it "objectionable." But he said, "Personally, I believe there is a lot of objectionable material on the air. That doesn't necessarily mean it's indecent."