Tom Keith, 64, the virtuoso sound-effects man who for more than 30 years was a one-man band, zoo and noisemaker on Garrison Keillor’s popular radio program, “A Prairie Home Companion,” died Oct. 30 on the way to a hospital in his home town of St. Paul, Minn.

The cause of death was cardiac arrest, said his twin sister, Terry Green.

Mr. Keith was a constant creative presence on the Saturday variety show, which first aired in 1974 and is distributed by American Public Media on 600 radio stations.

For the 4 million weekly listeners who tune in to hear about the news from Lake Wobegon, the travels of the philosophizing cowboys Dusty and Lefty and the misadventures of the hapless detective Guy Noir, Mr. Keith was not a technician but a comedian in his own right.

A former sound engineer, he received little training in acting but had an innate talent for mimicry. He was able to produce almost any sound requested by Keillor, who writes the scripts almost entirely on his own, usually the day before the live recording, cast member Sue Scott said.

For the past decade, Mr. Keith participated mainly in recordings made at the show’s home venue, the Fitzgerald Theater in St. Paul.

Fred Newman, the sound-effects man who performs with the traveling cast, said in an interview Tuesday that Mr. Keith was an old-school radio talent who played his table of sound-effects props “like a piano.”

Mr. Keith made many of his tools himself. He discovered that bending a box of cornmeal mimicked the sound of footsteps in fresh snow. The galloping hooves of Dusty’s and Lefty’s horses were actually coconut half-shells that Mr. Keith clopped in a container of gravel. By rubbing a balloon, he recreated the sound of a ship’s ropes groaning in the wind.

He was “a connoisseur of Styrofoam,” he once said, having discovered that crushing egg cartons made the sound of breaking wood.

Mr. Keith’s repertoire also included dentist drills, explosions and almost any animal call. In one celebrated bit, he explored the imperceptible differences among the sounds made by caribou, elk, wapiti and other antlered beasts.

There was one animal he couldn’t “do.”

“I can’t do elephants,” he told a North Carolina newspaper in 1994. “I just don’t have the right lips.”

Keillor almost stumped him with another request: the sound of tires spinning on ice.

“One evening a car was stuck on the ice outside my apartment,” Mr. Keith told the San Diego Union-Tribune in 1987. “I just kept whistling and humming to try to simulate the sound. And fortunately the guy was stuck for a long time, and I was able to keep working on it until I got it. . . . Then I went down and helped him.”

Mr. Keith owed his career in part to the harsh Minnesota winters. In the early 1970s, he was a sound engineer on Minnesota Public Radio’s “Morning Show,” which Keillor hosted. When bad weather delayed Keillor’s arrival at the studio, Mr. Keith filled the air with music.

The two men bonded over the crack-of-dawn recording sessions, Mr. Keith’s sister recalled, and Keillor invited Mr. Keith to join the show as an on-air personality. He became the voice of the poultry-raising Poole brothers, Ed Jim and Jim Ed (one specialized in roosters, the other in attack chickens, according to the magazine Minnesota Monthly).

Mr. Keith followed Keillor to “A Prairie Home Companion,” first as an engineer and then, beginning in 1976, as a sound-effects man. He also took over from Keillor as a co-host of the “Morning Show,” a position he held for about 25 years before stepping down in 2008.

Mr. Keith continued to perform with “A Prairie Home Companion” until his death. Live audiences at the Fitzgerald Theater knew him by his trademark attire: sweater vest, bow tie and, sometimes, a pair of shoes hanging around his neck by their laces. They could be used for a quiet stroll or a quick getaway — whatever the skit required.

Thomas Alan Keith was born Dec. 21, 1946, in St. Paul, one of four children. Their father, a manager at the 3M company, had a “Johnny Carson-quick sense of humor,” Mr. Keith’s sister said, and regularly performed on local radio.

Although Mr. Keith grew up in a home full of play-acting and joke-telling, he was shy and was never the class clown, his sister said.

Mr. Keith’s service in the Marines, from 1965 to 1969, would later help him “do a fine drill instructor” voice, Keillor noted in a statement on the Prairie Home Companion Web site after Mr. Keith’s death.

After his military service, Mr. Keith graduated from the University of Minnesota, where he majored in speech and broadcasting and minored in theater, according to a profile by the Kansas City Star.

Survivors include his wife of 11 years, Ri Wei Liu-Keith of Woodbury, Minn.; his sister; and two brothers.

Mr. Keith once told a reporter that he would never walk around listening to music with headphones, as so many people do.

“I hear so much wonderful stuff everywhere I go,” he said.