Dr. Amar Bose was a professor at the Massachusetts Institute of Technology (MIT) for more than 45 years. But, it wasn't his teaching skills that earned him the 271st place on Forbes's 2007 richest men in the world list. Bose was better known for his work on developing better acoustic products, especially headphones through his company of the same name.

As a professor at MIT, he’d tell his engineering students the most important attribute an engineer can have is imagination.

“You can never make any more progress than what you can imagine,” Bose told the students. “I think it was Albert Schweitzer who said what is bad is not that man lives and dies, but what dies within man while he lives. Perhaps the most important thing that dies within man while he lives is his imagination.”

Bose’s personal imagination is legendary. Not only was he one of MIT’s most beloved professors, but he used his company, the Bose Corporation, to bring the world a long string of innovative products — including the first noise cancelling headphones.

Those headphones are a good illustration of Bose’s theory about imagination. On a flight from Zurich to Boston in 1978, Bose encountered the first of a new generation of electronic headsets that replaced the older pneumatic tube headsets that had been previously used for in-flight entertainment.

Stop the noise!

The new headsets — to be sold with Sony’s first Walkman portable music player the following year — weighed less than two ounces, rather than the heavier traditional headsets that weighed nearly a pound. Their development was an innovation in itself.

Bose was excited to try the new headsets on the long flight. But what began as pleasure, soon turned to disappointment. The cabin noise on the aircraft was so loud, it made it difficult to hear the music clearly over the new headsets. There had to be a better way, Bose thought to himself.

Bose took off the headphones and got out a note pad. He began to create a design that would eventually become the first noise cancelling headphones. The sketches he made on that flight before he arrived in Boston became the foundation for a breakthrough in headphone design.

Headphones that "listen"

Bose designed a system that would use a microphone inside the headphones to pick up all the noise occurring in the atmosphere around the user. That noise would then be sent to electronics that generated an equal and opposite signal within a fraction of a millisecond that cancelled out the sound before it reached the eardrum of the listener. That was his theory, at least.

When he returned to his office in Boston, Bose formed a team of engineers to work on his design. “It took over 15 years before we were able to make the concept work,” recalled Santiago Carvajal, a category business manager at Bose. “During that period, there were many people in the company who asked ‘why are you wasting your time on this technology?’ The concept that you could cancel sound with sound was like putting someone on the moon.”

But Bose was persistent and the research continued. When the research cost hit the $50 million mark, Bob Maresca, then head of the noise reduction group and now Bose’s president, had to give the astronomical figure to Bose, his former professor at MIT.

“Do you know how much money we spent on this?” Maresca asked Bose. “$50 million dollars! I’ll never forget his response. He said: '50 million dollars! If this were a publicly traded company, I would have been fired years ago!”

Undaunted by the huge expenditure, Bose ordered the research to continue.

"Go fly--an airplane"

By early 1986, the Bose design group was nearing a working model. About this time, Bose learned about the Voyager flight that Dick Rutan and Jeana Yeager were planning later in the year. The pair would attempt to circumnavigate the globe in an aircraft without refueling.

But because the Voyager’s engineers were trying to reduce the weight of the aircraft to save fuel, there was no insulation surrounding the cockpit. This meant the aircraft was extremely noisy inside and there was fear the crew might lose their hearing during the long flight.

This triggered Bose to offer the prototype headset as a solution. It worked during the flight, which was a major success. It put Bose noise cancelling headset technology on the map. Pilots everywhere demanded the headsets.

As a result, the noise cancelling headset was launched in 1989 — the Bose Aviation Headset. It was the first commercially available noise reduction headset in the world. It allowed pilots to hear their audio and communications more clearly and to listen at lower volume levels.

Award-winning design

Product improvements were introduced in 1995 with the Acoustic Noise Cancelling headset Series II, which was awarded “Product of the Year” by the Aircraft Owners and Pilots Association (AOPA). In 1998, the Bose Aviation Headset X was introduced, offering a breakthrough in performance with proprietary TriPort headphone structure.

Today, the Bose A20 Aviation Headset is the most advanced aviation headset from Bose, delivering significantly greater noise reduction in loud environments, improved comfort and a Bluetooth interface.

The military wanted noise cancelling headsets as well and Bose made special versions for combat. In 1993, the Bose Combat Vehicle Crewman Headset went into production for the U.S. Army. The contract was renewed for the Performance Improved Combat Vehicle Crewman Headset, now being used by the U.S. Army on Abrams Tanks and Bradley Fighting Vehicles. U.S. Air Force pilots flying C-130s and several other aircraft were also outfitted with Bose active noise reduction headsets.

In 2004, Bose introduced the TriPort tactical headset, used by infantry soldiers operating military Humvees, cargo trucks and other wheeled vehicles. Bose’s noise reduction technology in commercial and military applications was then leveraged for general purpose headphones.

In 1999, Bose introduced the first noise cancelling headphones exclusively for American Airlines first and business class customers. The headsets were popular, leading to the general introduction of the QuietComfort series in 2000. These general purpose headsets are used by consumers, broadcasters and professional monitoring sound in a wide range of adverse noise conditions.

Football coaches are picky

Another difficult challenge came in 2013, when Bose got a contract to design noise cancelling headphones for NFL coaches and assistants. The company had seven months to build the headsets for the 2014 pro football pre-season.

“It reminds me of the five years we spent going to upstate New York to do blast testing for headsets for tank vehicles,” recalled Maresca. “We learned they would hang the headsets on the gun turret and then blast. It would collapse our speakers. So we had to design speakers that could withstand that.”

Though such blast tests weren’t necessary for the NFL, about every other obstacle was. The NFL headsets were slammed, dropped and stored in freezing and rainy conditions. They were tested in extreme winds and carefully fitted for use over hats worn by coaches.

Some coaches preferred using headsets over one ear — in order to hear outside sounds with the other one. This was a new challenge. Bose built about 50 one and two ear headsets for each team. During the first season the headsets worked well, though Bose will do slight modifications for next season.

Adding digital technology

Since Dr. Bose sketched that early design on the flight in 1978, the technology has remained basically the same — though it has improved through evolutionary advances in digital technology.

“We’ve been able to substantially miniaturize the technology,” said Brian Maguire, a director in the Bose noise reduction technology group. “Digital technology has allowed us to make large scale improvements not only in the total level of active noise cancelling performance but also in the size of the package we are able to deliver to the end user. The headsets are now more physically comfortable and don’t have to be clamped as hard against the ear. We also enable better audio performance and users no longer have a separate battery module to weigh them down.

“Fundamentally, all these designs stem all from that original design by Dr. Bose,”Maguire continued. “Today, we refine the design by tailoring the response to the specific noise in the environment the headset is used in. We might also employ a different size driver to create that opposing cancellation signal in a louder environment. We like to know where it is going to be used and we design it to specially perform at its best in that location.”

As to the late Amar Bose’s persistence with his noise cancelling design, Maguire credited the inventor’s “incredible and intense curiosity for the unknown and persistence to bring new things to the world.

“When he designed these headphones, I think he was certain they could make a huge difference in people’s lives,” Maguire said. “That’s why he had the persistence to continue to invest in it. And ultimately he was right.”

Chalk it up to imagination.