Leo Beranek

The Electro-Acoustic Lab’s anechoic (or echo-less) chamber, nicknamed “Beranek's Box.”

The sound of silence

In August 1935, in the thick of the Great Depression, Leo Beranek was trying to figure out how to pay for grad school. It was over 100 degrees in the shade as he walked down Route 30 in his hometown of Mount Vernon, Iowa, when he came across a Cadillac with a flat tire and Massachusetts plates.

The driver wore a freshly pressed suit. Glancing at his own dungarees, Beranek figured he would help the stranger change his tire.

“What do you do?” the man asked, as Beranek dealt with the spare tire.

Beranek replied that he went to Cornell College there in town, and that math and physics interested him. “I want to go into radio.”

“That’s my field, too,” the driver said.

Beranek shared his plight of wanting to go to graduate school in spite of his family’s financial woes. Then he paused to ask the man his name. The response astonished him.

“You’re Glenn Browning? I just read one of your papers on the Browning tuner this morning.”

Beranek had just changed the tire of a prominent radio engineer and Harvard instructor.

Browning told him that he should apply to Harvard, which was generous with its financial aid, and that is exactly what Beranek did.

Over the course of his sweeping career, Beranek would become a professor at Harvard and MIT, solve critical acoustical problems for the U.S. Air Force and Navy, write 12 books on acoustics, architecture, and noise control, design several of the world’s most acoustically optimal concert halls, and found the pioneering consulting firm Bolt, Beranek and Newman. Now known as BBN Technologies, the firm started in acoustics and later moved to computing. Over the years it played a role in everything from designing the sound system for the United Nations headquarters to investigating JFK’s assassination to building the early Internet. In the midst of it all, Beranek even founded and served as president of WCVB-TV, Channel 5, in Boston.

He spent the war years at Harvard. After earning his doctorate in acoustical engineering in 1940, Beranek was soon approached by the U.S. Air Force to oversee the Electro-Acoustic Laboratory. His task: Figure out why pilots of long-range bombers were getting so exhausted in the air. The Air Force suspected that noise fatigue was to blame. 

In rapid fashion, Beranek and his team designed a lightweight acoustical blanket called “Fiberglass AA” that is still used to quiet the interior of aircraft today.

Their success led to another assignment and another question: Why was communication so difficult in the cockpit? Was it that pilots couldn’t hear as well at high altitudes, or that they couldn’t speak at regular volume? In late 1943 the Electro-Acoustic Lab found that the human voice decreases dramatically at low atmosphere pressure. Better microphones were needed to make voices heard in high altitude flight—especially above 30,000 feet. Crewmembers wore oxygen masks because the cabins were unpressurized in those days, and voice communication soon became nearly impossible. The Electro-Acoustic Lab worked with manufacturers to redesign in-flight microphones and earphones. 

Later, Beranek would move on to MIT and shift his focus to a lifelong love of music, earning a global reputation for his innovations in the acoustics of concert halls and opera houses. For his efforts in World War II, Beranek won the Presidential Certificate of Merit, and for his lifetime of achievements, he won a National Medal of Science.