Popular Mechanics (South Africa)
This changed everything:
Noise-cancelling headphones’ aviation origins.
AMAR BOSE WAS FRUSTRATED. It was 1978, and he’d planned to kill some of the time on his 6 000 km flight from Zurich to Boston by listening to music through some new, foamcovered (read: flimsy) headphones that Swissair supplied to the passengers. His enjoyment was foiled by the drone of the engines, which overpowered the lightweight headset. Fortunately, Bose was a professor of electrical engineering at MIT, and the head of his own electronics company, the Bose Corporation. By the time he had arrived in Boston, he had scrawled the first steps towards a solution to his sonic problem: noisecancelling headphones.
The idea had precedent – scientists such as Lawrence J Fogel in the ’50s and Paul Lueg in the ’30s had applied for patents on their own versions of the concept, for use in everything from concert halls to helicopters. But Bose came to the idea independently. And nobody had put the pieces together in a way that would work for consumer headphones.
‘In order to cancel a noise,’ says Dan Gauger, a member of the original engineering squad Bose put together to realise his vision, ‘you have to take all frequencies. For each one of those, you have to make a noise at the same frequency, of the same amplitude, but the opposite phase. So you have to combine a +1 with a –1.’ To accomplish this, and make the technology workable enough for mass use, Bose’s team incorporated a couple of crucial innovations of the ’70s, like a small electret microphone. It was composed of high-resistance material providing a permanent charge without needing a ton of voltage and current. Positioned near the entrance to the ear canal, the electret mic picks up sound so the circuitry can compare the noise outside the headphones to what you want to hear – your music – and produce that opposite phase sound. Then, you hear only the tunes.
Anyone who’s watched a school principal struggle with an oversaturated microphone and an ancient PA system knows feedback can be a nuisance when it’s accidentally generated. But when it’s tailored to zap unwanted noise, it can be your best friend.
Eight years and around $3 million later, Gauger and his colleague Roman Sapiejewski heard news of former USAF pilot Dick Rutan and co-pilot Jeana Yeager’s upcoming attempt to circumnavigate the globe in the Rutan Voyager, without stopping to refuel. But the plane had no sound-deadening. ‘We had 110 decibels in the cockpit,’ says Rutan. The risk of permanent hearing damage increases at noise levels of 75 decibels and greater when you’re exposed to it 24 hours a day,
as the Voyager pilots would be. In August 1986, the two Bose engineers showed up unannounced at Rutan’s door, and gave a demonstration of the noisecancelling tech. They got the go-ahead and started work on prototypes. With Bose’s headphones shielding their ears, Rutan and Yeager made their nine-day, non-stop flight that December.
‘That got a bunch of attention,’ says Gauger. ‘Within a month or so we found our first market: general aviation.’ Bose started manufacturing its Aviation Headset Series 1 in 1989, the first commercially available noise-cancelling headphones for private pilots. But it wasn’t until they patented TriPort technology, which allowed for smaller, lighter, more comfortable earcups, that Bose brought the tech to consumers with the first QuietComfort line in 2000. TriPort, Gauger says, is a way of efficiently using earcup volume by carefully placing holes behind the speaker inside the headphone to help generate more low-frequency sound, while still leaving plenty of room for passive blocking of high frequencies.
In the last 20 years, Bose’s headphones have advanced with the times. The company brought noise cancellation to the earbud format with the QuietComfort 20 in 2013. And as of 2018, Bose had 44 per cent of the noise-cancelling headphone market. But other brands such as Sony and Apple are driving their own innovation. Consumer electronics analyst Ben Arnold of the NPD Group, a market analytics company, finds adaptive noise-cancelling to be one of the most exciting developments. ‘You can block out different frequencies of sound while letting others in,’ he says. ‘That’s a big evolutionary step.’
What’s more, Brett Molesworth of the University of New South Wales School of Aviation led studies in 2013 and 2014, finding that noise-cancelling headphones reduced communication errors and improved task performance in aviation settings. But the benefits of noise cancelling have been realised beyond when you’re just listening to music or piloting a plane. The tech has also become a boon for employees in open-concept offices. A 2018 survey commissioned by streaming service Cloud Cover Music found that about two-thirds of workers feel that wearing headphones increased their perceived productivity, and 30 per cent used them solely to tune out ambient noise. And research led by Sun Yat-sen University’s Maojin Liang in 2012 found that noise-cancelling headphones may prevent hearing damage caused by listening to loud music over background subway and street noise.
Remote work has made the headphones even more useful. ‘Everybody’s working from home,’ says Arnold. ‘You’ve got multiple workers and kids learning. That’s another place where the technology can prove itself.’
‘Our ears are as important for engaging with the world as our eyes,’ says Gauger. ‘But you can’t squint your ears. Headphones can let you do that.’