Cut That Cacophony! Beyond Better Music, Active Noise Cancelling Headphones Help Reduce The Unwanted Sounds Around Us
Noise cancelling headsets for airline pilots were designed 40 years ago by Indian-origin engineer, Dr Amar Bose of MIT, USA.
His company, Bose Corporation, also launched the world’s first consumer noise cancelling headphones.
Today, the technology has been refined and digitised by other audio-electronics leaders like Sony and Blaupunkt.
Indians are discovering such devices have other uses — like buying a little peace and quiet!
Let me begin with a personal anecdote: I live in an apartment complex where the biggest dread is that an adjacent flat should not change hands.
This usually means a new occupant — and a week or two of incessant hammering, drilling, grinding to redo the place — all very noisy.
But I have a small solace: I dig out my prized possession — a vintage pair of ‘Quiet Comfort’ headphones crafted by Bose Corporation, US — arguably the world’s most respected brand for good audio quality.
The pair in question has sentimental value for me in addition to its utility.
It was the world’s first consumer headphones with built-in active noise cancellation. And it was presented to me (and to five other visiting Indian journalists) by Dr Amar Bose when we visited the hill-top global headquarters of Bose Corp., in Framingham, just outside Boston, Massachusetts (US), during a media event in 2005.
I realised quite soon that one does not have to use noise cancelling earphones just to enhance the music experience. One can use them just to reduce, if not eliminate, the level of outside noise.
The idea of cutting out outside or ambient noise from headphones tuned to music, occurred to Dr Bose, then a professor of Electrical Engineering at the Massachusetts Institute of Technology (MIT) in 1978, while taking a long flight to Europe.
He found that the incessant noise and vibration of the aircraft engine added to the air-conditioning in the cabin, seeped through the headsets provided and spoiled his enjoyment of the music. This set his mind working — how to cut out the unwanted external noise.
The principle was known from the 1950s and indeed, is attributed to the American engineer, Dr Lawrence Jerome Fogel. But it was Bose and his team at the company he had founded in 1964, that translated the theory into a product. The theory went like this:
Fighting noise with anti-noise
If sound waves carrying unwanted sound (ie, noise) hit the headset, cancel them by creating sound waves that are equal and opposite in polarity and thus cancel the net sound to zero. In other words, fight noise with anti-noise. The principle is known as ‘destructive interference’.
This is done by embedding the headphones with tiny microphones — and a processor that takes the unwanted sound received by the microphone and ‘cancels’ it electronically.
This leaves the wearer free to clearly receive the sound he or she wants to hear — music, TV, movies, whatever.
The electronics mostly work on the lower end of the audible frequency band which ranges from around 20 Hz to 20 Khz, so continuous background sound like street noise is cut off.
But it is less effective in handling sharp, shrill sounds — so a siren, a car horn or a hammer in use, may get through. This remains true even today.
Dr Bose found a ready market in the commercial aviation industry, which soon equipped pilots with Bose noise cancelling phones to cut out the intense noise in the cockpit.
It took another 14 years before the Bose Corp. launched the first consumer version of its active noise cancelling headphones, called Quiet Comfort, in 2000 — and since then lay users have been able to listen to what pleased them, while cutting out the cacophony around them — on flights, in busy public areas — or like me when the neighbours start civil construction.
The technology of fighting noise with noise is called Active Noise Cancellation. It requires the headset to have special circuits built into it with a battery to power them, which has made such equipment rather heavy to wear — till now.
In view of the loose use of the term noise cancellation by many products, it is necessary to distinguish active noise cancellation from passive noise cancellation.
The latter has no special circuits and uses things like soft cushioning or rubber-like cups to surround the ear and muffle the unwanted outside noises.
It is nearly two decades since my vintage pair of wired Bose Quiet Comfort headphones were made — and I could recently appreciate how leading audio electronics companies like Blaupunkt and Sennheiser in Germany, Beats in the US and Sony in Japan, have refined and improved active noise cancelling audio technology, in recent years.
Made-in-India brands like BoAt too, have helped bring down the price of noise cancelling technology in audio devices.
Bose itself, whose latest in the on-ear noise cancelling range is Quiet Comfort 45, introduced the technology to in-ear phones in 2020 and called them Quiet Comfort Earbuds. Now, many others have done likewise.
Sony launches lightest noise cancelling headphones
I had the opportunity to try out a very recent model of a wireless active noise cancelling over-the-ear headphone — Sony’s WH-CH720N — which the company has recently launched in India.
The electronics of noise cancelling are all-digital these days, the chips that do the work are smaller, lighter and faster — which means they don’t call for a pair of penlight sized batteries, but use a tiny rechargeable Lithium-ion cell.
In the CH720N, I could charge the new headset in about 30-40 minutes and the makers assure that it is good to go for 50 hours, 35 hours if you keep the noise cancelling circuit active since they consume power.
It was also remarkable how light the Sony headset was in spite of the onboard circuitry and the V1 chip they use for noise cancelling– just 192 grams. They also use a special Wind Noise Reduction structure around the built-in microphone, useful for outdoor users.
To get the full benefit of noise cancelling one should install and link the headphones to the Sony Headphones Connect app on your smartphone. This takes the control of the ambient noise beyond the simple Ambient/Noise Cancelling on-off control and lets you adjust the ambient sound to any one of 20 levels.
This can be very useful, if you are waiting for a train or plane — you don’t want to miss any loudspeaker announcements. But if, like me, noise cancelling equals welcome silence, you can go all the way.
The CH720N works very well when Bluetooth-synced with your phone – and the phone conversations are crystal clear.
So is the sound when I connected the headphones to my television set via Bluetooth and watched a movie which had 4K and surround sound tracks. The audio experience was far superior to the TV’s built-in speakers.
The Sony WH-CH720N has an MRP of Rs 14,990 and is said to be the lightest from Sony’s over the ear wireless noise cancelling headphone range.
However online sites like Amazon and Flipkart offer it for as low as Rs 9,990— which is a very sound value (pun intended!) for the dynamically adjustable noise cancelling feature alone.
Sony also has more advanced noise cancelling head-ware with multiple microphones, priced at Rs 25,000 – Rs 30,000.
When Simon and Garfunkel celebrated the ‘Sound of Silence’ on the soundtrack of that seminal 1967 film, ‘The Graduate’, it was a metaphor for the mental cocoon in which the mixed-up hero, played by Dustin Hoffman lived.
Today, that phrase is high praise for technology that cuts out the noisy world around us — and incidentally, delivers great music.
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