When engineer William Kroll of Minnetonka wasn't inventing or designing, he traveled to some of the hidden reaches of the world.

Kroll, who founded Wm. H. O. Kroll & Associates to consult in acoustic engineering, died Oct. 1 in St. Paul of a stroke. He was 78.

After getting his bachelor's degree in electrical engineering at the University of Minnesota, he went to work for U.S. Steel in Venezuela, scouting locations and designing communication and navigation systems. He and his family lived there for six years.

On a month's trek in 1965, he found a tribe in Brazil that had not been influenced by outside civilization, according to an Oct. 27, 1996, Star Tribune article.

On his adventures, whether in Africa or South America, he strove to learn the natives' languages and cooking.

He said of the Brazilian tribe: "They had never seen a clothed person ... or a match or a metal knife."I studied and learned about native cultures and food at every opportunity. I wanted to see how they lived, what foods they ate, how they cooked."

His son Mark of Orono said Kroll cooked those authentic dishes at family celebrations.

"He had incredible confidence, a can-do attitude" that he imparted to his children, and always found time to personally help needy people.

"He had an absolute kindness and respect for people," said his son.

In 1965, Kroll moved to Minnetonka and founded his acoustics business. He helped to keep bad sounds out and good sounds in -- in performance halls, churches and classrooms.

His sound and vibration-prevention work can be found in the construction of Interstate Hwy. 35E as it runs by United Hospital in St. Paul, and in south Minneapolis schools that are in a flight path.

"He was an acoustical genius, creative and inspirational. He was a true advocate of the performer," said Edward Kodet, a Minneapolis architect.

Some of his acoustics projects include: The University of Minnesota's West Bank Union performance hall, Rochester's Mayo Auditorium and Minnetonka's St. David's Episcopal Church.

In the 1970s, he invented an electronic method to weigh objects that defy use of a scale, including NASA's space shuttles.

He had a half dozen patents, including some for gear used in the sonic inspection of micro cracks in train wheels, for a hot plate and an electric lighter.

In recent years, he personally remodeled a farm house in Long Prairie, near the farm where he was born.

He was a veteran of the Army, having served in occupied Italy in the mid-1940s.

He could communicate in about 10 languages, four of them fluently. At the time of his death, he was learning Greek.

In addition to his son Mark, he is survived by his wife, Irene, of Minnetonka; sons Billy of Medina, Bobby of Medina, Karl of Maple Grove, Kai of Plymouth, Fritz of Minneapolis, and Richard of Plymouth; daughter Connie Olson of Excelsior; brother John of Long Prairie; sisters Irma Johnson of Lowry, Minn., and Esther Hartwig of Albany, Minn., and 21 grandchildren.

Services will be at 10 a.m. today at Our Savior Lutheran Church, 23290 Hwy. 7, Excelsior.



Ben Cohen • bcohen@startribune.com