Bill Cerri, whose classical music had soothed and whose baritone had entertained harried commuters for almost 20 years in his job as host of WETA-FM's (90.9) morning-drive show, suffered a cerebral hemorrhage while he was on the air yesterday and died several hours later.

Cerri, 60, who had planned to take medical disability retirement from the noncommercial station on Aug. 24, was talking to his audience and apparently preparing to play an aria routinely aired just before the 9 a.m. news when he began to garble his words, got up from his open microphone and walked out of the studio and into a hallway.

Joe Davis, WETA-FM's chief engineer, said he was making copies at a copying machine down the hall from the studio when he first noticed the on-air silence. Davis said he was not immediately alarmed, however, because silence before a recording starts is "not unusual with classical music." But then, said Davis, "I looked up and saw Bill and noticed something was wrong. He walked into one of the offices and turned around. He said he was looking for the studio. He was very disoriented."

Davis said he sat Cerri down in the station's record library, got some assistance from senior station producer Mary Beth Kirschner and then called an ambulance to the Arlington studios.

"Our listeners were right on top of the situation," Davis said. "Gosh, they knew that something was wrong with Bill. They were calling immediately." Davis said the phones and programming went unattended "until we got it under control."

In all, there were nearly four minutes of silence until Davis rejoined the National Public Radio newscast at about 9:03. After the news, Davis followed Cerri's playlist, beginning with Haydn's "Cello Concerto in C," until midday host Marilyn Cooley slid into the announcer's chair at 9:15. Cooley later told concerned listeners that Cerri had "fallen ill and was taken to the hospital for observation."

Cerri was "conscious but incoherent" when taken to the National Hospital for Orthopaedics and Rehabilitation in Arlington. He died nearly four hours later at 1:38 p.m. with his son, Bill Cerri Jr., and other family members at his bedside. Cerri's marriage had ended in divorce.

Cerri's brother, Dick Cerri, who hosts the long-running folk music program "Music Americana" Sundays on WLTT-FM (94.7), was notified of his brother's stroke while vacationing in Maine.

Although neurologist Richard Wittenborn, who was Cerri's attending physician, declined to discuss Cerri's case in particular, he said that there generally is little that can be done to stop a stroke.

"Often with this kind of stroke, once the process is set in motion, there are no effective therapeutic options," Wittenborn said.

WETA listeners were told of Cerri's death shortly before 2:30 p.m. by announcer Robert Aubrey Davis, who described Cerri as "a man that I have known since 1976 and listened to since I was a boy, and {who} was a friend as well."

Members of the station's staff were stunned and saddened by their colleague's sudden death. Robert Aubrey Davis said, "We thought hard about what might be the most appropriate thing to celebrate his life and his passing" and had chosen to follow the announcement with a 40-minute musical tribute -- selections from Verdi's Requiem performed by the Vienna State Opera Chorus and the Vienna Philharmonic.

"It's a shock. The finality of it is horrible. Certainly everyone is deeply saddened," said WETA-FM General Manager Tom Livingston, who was summoned to the station from a senior staff retreat in Elkridge, Md., after Cerri's stroke. "There are few things that are more intimate than a radio station where people work together 24 hours a day. There is a bond. This is like losing a member of your family."

Livingston said Cerri "was great. He was so Italian. We really used to slug it out. Bill was an example of how you can be successful by being yourself."

Cerri had several minor strokes a number of years ago and two years ago underwent a heart bypass operation. He suffered from Parkinson's disease and in late May announced he would retire from WETA after more than 20 years, most of which were spent as the morning-drive announcer. Cerri had planned to work on special projects for the station after leaving the rigors of daily morning radio and was particularly looking forward to his retirement day because it meant the fulfillment of a long-held dream: He was to conduct the Air Force Band during the annual "Christmas in August" concert at the Sylvan Theater on the Washington Monument grounds. He founded the event in 1971.

Because of the physically debilitating Parkinson's disease, Cerri "was contemplating a life without motor skills. He had learned to live with it," Livingston said. "It was a tremendous act of courage. He was looking forward to his retirement with courage and bravery."

In an interview with The Post two months ago, Cerri said, "My best years have been spent at WETA and that's no crock. That's why I stayed here 20 years. It was the only station where I wasn't fired."

Cerri, who discovered that "the easiest way to communicate with an audience is to talk to one person," left his hometown of Utica, N.Y., in 1950 and came to Washington to work as an evening classical music announcer on the old Continental FM Network, then heard on WASH-FM (97.1). He later worked at WGMS-AM/FM (570/103.5) and WOL-AM (1450).

His morning show on WETA attracted 150,000 to 200,000 listeners weekly, based on Arbitron's winter surveys, according to WETA Program Director Tim Owens.

Livingston, who has been searching for Cerri's replacement since the host announced his decision to retire, said yesterday that staff announcer David Ginder will perform the morning duties until a permanent host is found.

Last April, Cerri, along with Robert Aubrey Davis and announcer Mary Cliff, was honored for his contribution to WETA with a gala celebration at the National Building Museum.

"A part of my life will be missing," said Cliff yesterday. "He was a good friend and a great teacher. He was unpredictable and a lot of fun." Cliff, who worked with Cerri for two decades, added "If you have to go, I guess this is the way to go -- in the saddle doing what he loved to do."

Cerri, whose trademark sign-off each morning at 10 was "Thank you for listening," always emphasized the word "you."