Noise blocking and noise cancelling

What are the key differences between the types of noise-reduction technology?

What are the key differences between the types of noise-reduction technology?

If you’re searching for your next pair of headphones, chances are you’re coming across a lot of technical terms that sound very similar but are just different enough to confuse you. Do I want to cancel noise or block noise? And is there really a difference? The answer is “Yes”. Knowing the right terms to search for is essential and will lead you to the right tech, the best product to get the job done and, hopefully, the experience you seek. Whether you want to tune in and focus, or drown out the world, we’re here to put you on the right path.

There’s a huge amount of technical jargon that’s used interchangeably, and it shouldn’t be. So, we’re going to clear up the confusion with some simple, straightforward explanations. We’ve broken it down to two distinct approaches for managing noise with headphones or earbuds—noise cancelling and noise blocking. We’ll explain what they are, how they are different and what they’re best suited for—without getting too technical or making your eyes glaze over.

Man using the swipe controls on the Bose Sport Earbuds


Also known as passive noise reduction or noise isolation

A term like noise blocking makes it sound like a high-tech solution, but it’s actually very low tech. In fact, noise blocking can be as simple as sticking your fingers in your ears. Try that next time you hear a siren, and notice how it creates a physical barrier between you and the offending noise. This is known as passive noise reduction, another term you’ll probably come across in your search. Anything that covers your ears can passively block noise. There’s nothing electronic about passive noise reduction, which means there’s no built-in technology or microphone, and nothing needs to be powered on.

As low tech as it is, noise blocking is an integral part of headphone design because, when done right, it’s the first line of defence against unwanted sounds. That’s why having a good seal on an earcup, or a snug fit with an earbud, can make a huge difference in performance. In this case, the science is more about biology than technology. There are so many shapes and sizes of the human ear to be studied, measured and tested. We’ve scanned hundreds in the pursuit of a better fit and comfort, to ensure optimal noise blocking. The latest StayHear™ Max tips used with our true wireless earbuds are a testament to the importance of human form factors in our innovations.

The bottom line: While noise blocking is effective, it needs to work in tandem with a technology like active noise cancellation in order to lead you to a more sophisticated solution.

Woman using her smartphone, wearing QuietComfort 35 wireless headphones II


Also known as active noise cancelling or active noise reduction


Airplane icon


Office building icon


Bus icon


Noise cancelling is a common term, and it may be the very thing you’re looking for. It’s different from noise blocking and passive reduction because it involves active technology. Bose was the first to use Acoustic Noise Cancelling™, or ANC, in headphones, when we invented the category over 20 years ago—a legacy that will always be tied to our brand. We could talk ANC all day long, but let’s just cover the basics.

Noise cancelling headphones have powered tech, which means energy (like a rechargeable battery) is needed in order for them to work. Remember, even without power, you’re getting the physical benefit of noise blocking by simply wearing the headphones. When you turn them on, that’s when the technology kicks in.

How does noise cancelling work?

Noise cancelling headphones monitor the sound around you, preventing unwanted noise from ever reaching your ears. Miniature microphones in the earcups or earbuds listen to outside noise frequencies and emit the exact opposite signal, to effectively “cancel out” both sets of sounds when the soundwaves collide. Our acoustic engineers explain that it’s a bit more complicated than that, since battery power, signal processing and noise blocking all play their part in creating the greater system that is “noise cancelling”. But you get the gist, right?

Where noise blocking is a physical barrier to keep out sound, noise cancelling happens silently in the background, creating an audio “barrier”.

When are the best times to wear noise cancelling headphones or earbuds? This tech is perfect for situations when you’re serious about enjoying your music, audiobooks, podcasts, shows or movies without external noise getting in the way. Noise cancelling headphones are becoming a part of everyday life, with more and more people using them for work, calls, travel and focused time at home.

The sound waves of noise cancellation in Bose Noise Cancelling Headphones 700

Hopefully, we’ve untangled the differences between noise blocking and noise cancelling. Now that you have the right terms, finding the right tech all depends on how and where you want to manage the sounds around you.

Product availability may vary by country.

How to choose the best noise cancelling headphones and earbuds
Buying tips: Noise cancelling headphones