Headphones incorporating noise cancelling technology make a world of differenc

The demo is about to start. The product manager asks the handful of tech journalists in the room to plug in earphones. We obey. The music is a mix of blues and jazz, with every note, every strum of the guitar as clear as it can be. There is also an extra large screen in the room, which strangely enough, shows a street in a busy South East Asian city - it has nothing in common with the music we are hearing. We are soon asked to take off the earphones. Soon as we do, our ears are assaulted by high-decibel noise from the TV. It is loud enough to make the room vibrate. We quickly turn back to the earphones - the Bose QuietComfort 20 to be precise - and the TV sounds promptly disappear.

The demo has the shock and awe effect that US audio equipment giant Bose Corporation brings to all its events. But it is also a testament to the power of the noise cancelling technology that Bose's founder, the legendary Amar Gopal Bose, who passed away recently, pioneered in the mid-1980s. Noise cancelling is slowly becoming common in high-end headphones. It is also becoming a necessity for many as sound pollution goes up several notches with every passing year.

So, what exactly is noise cancelling? There are two variants to this technology - active and passive. In active noise cancelling, as in the Bose device, headphones create a sound of their own to negate the surrounding sound. It does this using a microphone that listens and then creates waves that counter the noise frequency.

Active noise cancellation (ANC) works best when the noise is consistent or cyclical, like that of a plane or a train. It is not able to keep out the sounds that don't stick to a pattern, like the squeal of a baby. Passive noise cancellation is simpler and just prevents all kinds of noise from reaching the ear.

Most headphone manufacturers now have a noise cancelling product. The device comes in different shapes and sizes, with designs ranging from in-ear to on-ear. ANC, however, requires power in the headphone, and in the case of in-ear designs, an extra controller, where the noise cancelling is achieved.

Blaupunkt, the German company known more in India for its car audio systems, recently started selling premium headphones, including the CN-112, with noise cancelling.

Marketing Manager Preeti Bakshi says the use of this technology is no longer limited to high-flying executives. It is slowly becoming popular with those who want a premium sound experience and the facility of enjoying their music and movies in any environment.

People, however, still don't know much about this technology. "Many have never experienced a quality active noise cancellation product at work. Once they do, it is hard to resist, considering the amount of time today's users spend listening to music," she says.

In the last few years, this technology has also evolved. The Bose QuietComfort 20, which will be sold from September for Rs22,388, for instance, has an aware mode that lets you listen to certain kinds of sounds, such as a flight announcement or someone trying to talk to you, while blocking out everything else. The Blaupunkt CN-112, which costs Rs9,990, lets you adjust the level of noise cancellation so that you are not completely cut off from your surroundings. If you simply want peace and quiet, you can switch on the ANC without any music.

The same technology is also being used in other products, such as Bluetooth headsets that reject ambient noise and transmit only the voice of the caller. The new Lenovo Thinkpad Twist has dual-array noise cancelling microphones to ensure video conferences have crystal clear audio, unaffected by other sounds in the environment.

The only catch: though these headphones have been getting cheaper, they are still pretty costly. That is why some buyers end up with cheaper headsets with large ear cups that block noise without any digital sleight of hand. Not everyone can afford the price of silence.