Active noise-cancelling headphones feature noise-suppressing audio technology to help reduce ambient sounds.

During our day our ears are bombarded with a range of background noise and you can take action against this by using noise reducing headphones (often referred to as noise-cancelling headphones).

From people talking in our office, to the rumble of the train on our commute home, we don’t actively ‘hear’ many of the sounds that surround us but our brain is constantly working behind the scenes to filter them out so that we can keep concentrated to the task at hand. This can add to our cognitive load so we feel more tired or irritable than we should.

For example, we know that environmental noises have a detrimental effect on our well-being when we fly.

Research in 2011, led by Dr. Brett Molesworth¹ suggested that as people become exposed to (aircraft cabin) background noise for long periods while in the air, they suffer from negative effects, including;

1. They are more likely to experience mental fatigue
2. They have a decreased ability to recall information
3. They experience higher levels of reported stress and they perceive their workloads as more arduous

Sony wireless noise cancelling headphones MDR-ZX770BNB

So if we know that some types of background noise, like the drone of an airplane cabin is detrimental to our feelings of comfort and can induce stress, this might suggest why we feel distracted and more tired over long periods of time in a busy environment where we need to concentrate (to generate ideas or to check the details in an important report, for example).

If you want to relax more by reducing the working noises around you, you have two routes; either block it out by sealing your ears away noisy people and things around you or you can employ a combination of blocking out the sound and masking it with a sound processing system.

How Does Headphone Noise Reduction Happen?

It’s important to mention here that it’s very, very difficult to completely block all noise from your ears, or completely isolate the music or movies you want to playing into them. If you are investing in some noise reduction kit, we suggest that you have three options;

Noise reduction by headphone leaves you with three options, by ear protection, by active noise cancellation, and headphones

Ear Protection

The greatest level of noise reduction is usually offered by ear protection products like earplugs and headband ear defenders, whose primary function is to protect your ears, not to offer you the sounds from your latest Spotify playlist. They exist to fundamentally seal your ears away from all noise and while some ear defenders (like the ones worn by stage crews and racing team pit crews) are also headsets which feature sound and a microphone for radio communication. Unless you are working around a jet plane rather than sitting in it, it’s somewhat unlikely that ear defenders are going to be on your list!

Headphones

Like their distant, ear defending cousins, isolating headphones use an over-the-ear technique (pop them over your ears) or an in-ear approach (pop them in your ears) to seal noise away from your ears. All headphones could really be called noise isolating because no matter how inexpensive or beautifully packaged they were, all earphones will have some noise reduction capability (but it could be really small, like open-backed headphones) so if you want to rely on this style of earphone to block out sounds, we strongly urge you to try out a pair in a shop before you commit, because a headphone’s isolation personality is shaped by the quality of the materials used and the style of the headphone (closed back headphone, verses an open-back headphone, etc.).

Active Noise Cancellation (ANC)

Noise cancelling headphones, like the pair of Sony MDR-ZX770BNB take the best features of noise-isolation and on top of this apply an active, always on-the-go audio processor which listens to your external soundscape and reverses this sound.

Many models of noise-cancelling headphones can now connect wirelessly to your devices via Bluetooth

Reversing the Sound – Active Noise Reduction

Reverse the sound? What an earth are we talking about?

Active noise cancellation headphones like our Lindy BNX-60 house an onboard audio processing circuitry that, via external microphones, listens to your surroundings, and then attempts to produce an inverted sound wave, the opposite audio picture of your environment. This blanket of negative noise is continually integrated by the headphones into their audio output. This method of noise reduction is called ‘‘destructive interference’ and presents some of the best noise cancelling advances in the world today, so good that it’s used by airline pilots to communicate with air traffic control at 32,000 ft.

Headphones like these will often quote their noise cancelling capabilities in tested environments at a specific frequency range (the type of sounds they can mask). For example, Audio Technica’s ATH-ANC9 claim 95% noise reduction at the lower frequency range of 200hz.

It’s important to remember that you shouldn’t use headphones or active noise cancelling headphones as replacements for ear protection equipment in loud environments as without sufficient protection you could damage your hearing.

Some Final Things…

• Batteries – Active noise cancellation headphones relies on a small power source; hence these headphones either come equipped with an on-board rechargeable battery or require an alkaline battery replacement every now and then.
• Uneasy – some people just don’t get on with ANC, there are sporadic reports that these headphones can produce sensations of being underwater or nausea, (while this is very infrequent it’s another reason to try them out first)
• Stay safe – Noise reduction headphones don’t discriminate between noise! When you hear less around you, you could be prone to accidents or you could miss important warning sounds. Never using active noise cancellation while driving or cycling, or operating machinery that relies on audible safety warnings.

[1] Molesworth, B., Burgess, M. and Kwon, D. (2013), “The use of noise cancelling headphones to improve concurrent task performance in a noisy environment” Applied Acoustics, 74 110-115.

About Paul Cherry

Paul is the founder of Place Over Ears and came up with the idea of hiring headphones door-to-door after a train ride to London with his mum in 2007. Launched in 2015 with just 6 pairs of headphones, Place Over Ears' hire service now supplies audio kit to UK and international customers.