How Do Noise-Cancelling Headphones Work?

Oct 8, 2020

Category: Tech

Over the last few years, noise-cancellation technology has increasingly permeated every segment of the headphone industry, with everything from over-ear headphones to tiny true wireless pairs boasting the silencing tech. As the feature has become increasingly standard fare, a variety of different noise-canceling types and technologies have emerged, each setting out to tackle a specific problem or issue. But as the field of noise-canceling has broadened, it’s become increasingly difficult to wrap your head around and comprehend how the technology works and what distinguishes certain types of noise-canoeing tech from others.

And with the technology only looking to become more ubiquitous in future years, we thought we’d take a moment to unpack noise-canceling technology as a whole, examining the history and early uses of noise-canceling, as well as delving into the different types of noise-canceling technologies along with a cursory explanation of each. Furthermore, we’ll also be exploring the different types of proprietary noise-canceling technologies and features that are currently on the market, plus our picks for a few excellent options for anyone that happens to be in the market for a solid pair of modern noise-canceling headphones.

The Early Sounds Of Silence

A Brief History Of Noise-Cancellation Technology & Development

Interestingly, the concept of noise-cancellation predates the exists of the technology itself. In 1933, German doctor, Paul Lueg submitted a patent that involved using phase-advancing waves to cancel out sine wave tones, as well as inverting polarity to mirror and mask out sounds from a speaker. Three-years later—which is presumably how long it took the German patent office to make sense of Lueg’s concept—the patent was granted, though unfortunately for Lueg, 1936 didn’t possess the audio technology or hardware needed to bring his now-patented concept to fruition.

In 1950, Dr. Lawrence Jerome Fogel—a celebrated pioneer in evolutionary computation and human factors analysis—picked up where Lueg left off, harnessing the advancements made in audio hardware in the post-WW2-era to make the German doctor’s idea a reality. Dr. Fogel felt the technology could be best utilized by the aviation industry, and more specifically the helicopter sector, which was still producing ridiculously loud machines in the middle of the century. The successful implementation of the technology earned Dr. Fogel the unofficial title of “the Godfather of Active Noise Cancellation”—though the Brooklyn-born Ph.D. is also credited for being the father of evolutionary programming.

By the late 1970s, Dr. Amar Bose got the idea of producing a civilian pair of music headphones that featured active noise-cancellation technology while on a loud flight, ultimately prompting Bose to develop a prototype pair of active noise-canceling headphones. In the 1980s, fellow German brand Sennheiser would go on to develop its own pair of active noise-canceling headphones, marking the first-ever production pair to come to market, albeit they were aviation headphones (or “headsets rather”) for pilots.

Like most electronics, the advancements that occurred over the subsequent years allowed noise-canceling technology to grow more and more powerful while taking on increasingly compact forms and being manufactured for lower and lower prices. These factors have allowed active noise cancellation to go from a premium feature reserved for elite headphone models, to an increasingly common element on mid-tier offerings. Additionally, active noise-cancellation has started to pop-in in the automotive world, where the technology is being used to drown out wind and other road sounds while still allowing certain vital traffic noises to be clearly heard.

Photo: Bose Noise Canceling 700

Passive, Active, & Adaptive

The Three Main Types Of Noise Cancellation

While every form of noise-canceling strives to achieve the same basic result of mitigating outside sound, this technology can be produced using a number of different methods. Below, we’ll explore the three primary forms of modern noise-cancellation technology.

Passive

Passive noise cancellation doesn’t actually involve masking or canceling sound waves, and instead simply refers to blocking out noise via preventing vibrations from reaching the ear. This is typically achieved through an insulating layer or blockage, such as earbud tips that block external sound from entering the ear, or headshells that create a seal to shield the listener from external sounds. While passive noise cancellation is by far the cheapest form of the technology, high-end versions will often utilize vibration-absorbing and/or mitigating materials.

Active

Active noise cancellation works by using microphones to listen to the outside environment, and then produce, what in laymen’s terms can be described as an “inverted” or “mirrored” sound that essentially cancels out the original external noise. By adding what’s essentially the “opposite” of a particular outside sound and/or frequency, that external noise can be masked to the listener.

Adaptive

Rather than just actively canceling external sound, adaptive noise-cancellation does so, while constantly scanning its own environment and surroundings in order to constantly make minor adjustments in sound level and fine-tune the audio to optimize listening, and more effectively mitigate external noise. Put more simply, if the surrounding environment is quiet, adaptive noise-canceling will turn down the cancellation strength, or vis versa will increase noise-canceling as needed as the environment gets louder.

An Auditory Balancing Act

How Noise-Cancelling Technology Works

To fully grasp the finer points of active noise-cancellation it helps to at least have a tenuous grasp on how sound works in general. Put simply, sounds are essentially made up of vibrations that are delivered in waves which we describe, view, and chart using the sound’s amplitude (represented on the Y-axis), wavelength (represented on the X-axis), and frequency. Active noise-cancellation works by using tiny microphones that are embedded into the outside of the headphones in order to scan for external noise.

When this noise is detected, a built-in computer charts these sound waves, before delivering a version of the same external sound that’s now “out of phase,” meaning it has a mirrored shape that’s opposite of the first sound save. When these sounds are combined, it creates an effect that cancels out the noise to the listener, known as “destructive interference” or “wave phase cancellation.” Where the first external sound wave’s shape might have a peak, it’s opposite will have a valley in the exact same place. And this mirrored process gets repeated over and over continuously drowning out outside noise.

To help better convey the idea, let’s compare sound to changes in temperature. If the goal of active noise-cancellation is to reach a neutral sound level, let’s apply the same concept to a bucket of water — though, instead of aiming for a neutral sound, we’re aiming for a neutral temperature of, say, 50-degrees. If the outside environment heats up by 20-degrees (or if there’s loud external sound), we can cool the water by adding 30-degree water, thereby canceling out the outside variable to remain at our neutral target. And in the same way, active noise-cancellation is just producing sound waves that are the complete opposite shape as the external sounds in order to achieve a neutral effect.

It’s also worth noting that, despite the enormous strides made in active noise-cancellation technology across the last few years alone, the technology still struggles in environments with enormous and constant variations in pitch, frequency, and wavelength. This means a pair of high-end ANC headphones will be markedly more effective against the constant droning sound of an airplane engine than it will be at canceling out the cacophony of sounds heard when walking through the floor of a casino.

Just as important as the algorithms, digital signal processors, and noise-canceling technology itself is the transducers being utilized on a given pair of headphones. The more sensitive and accurate a pair of ANC headphone’s external microphone is, the better it will be able to detect and deliver the correct sound waves needed to achieve destructive interference.

Name Brand Noise-Cancelling

Proprietary Noise-Cancelling Tech

As active noise-cancellation has grown increasingly popular, a growing number of electronics brands have begun introducing their own proprietary ANC features and functionalities that build off of the existing technology to afford additional utility or convenience. There are obviously many different proprietary versions of this technology currently on the market, though breaking down these common modes should help to give you a better sense of the various types that exist.

Conversation Mode

A proprietary feature unique to Bose, Conversation Mode piggybacks on active noise-cancellation and gives headphones a bit of added convenience. By pressing and holding the Noise Control button on a pair of Bose headphones, Conversation Mode is activated, which pauses music playback control and kills the active noise-canceling so you can easily have a conversation or fully hear your surroundings. The coolest aspect of this feature is that it utilizes the built-in external microphones, which are normally used to scan for external sound in order to generate an “opposite” sound wave (for the purpose of active noise cancellation) to relay all outside sounds directly to the listener, giving them superhuman hearing without having to ever remove their headphones.

Transparency Mode

Transparency Mode is a feature found on Apple Air Pods (and Air Pods Pro) that, like Conversation Mode, offers a unique take on semi-active noise-cancellation. When turned on, Transparency Mode limits the overall strength of the noise-canceling, while continuing music playback, allowing music to be heard while simultaneously being able to hear certain vital external sounds such as car horns and traffic, PA system announcements, and human conversation. The mode also utilizes a special algorithm that helps the user’s voice to sound natural through the altered sound of noise-cancellation.

TalkThru

A technology invented and utilized by JBL, TalkThru is similar to Transparency Mode but differs in a few key areas. JBL’s TakThru Technology lowers the volume of music playback while at the same time activating speech-optimized, noise-canceling microphones, thereby allowing for easy—and fully audible—conversations without having to remove your headphones. This particular feature is fantastic for using at the office or when working from home, as you can engage in quick chats and then seamlessly resume playback of your music, podcast, or whatever you happen to be listening to.

AmbientAware

Ambient Aware is another piece of active noise-canceling functionality offered exclusively by JBL. This feature doesn’t affect music playback, though it increases the level of external ambient sound that can be heard. This is ideal for applications such as exercising or running, where you want to hear your music, but also want to be privy to the sounds of traffic or other vital noises. Best of all, this feature is fully adjustable, so it can be tweaked to suit a particular environment or user’s preference.

Photo: Sony WF-1000XM3

Leading ANC Options

Three Of The Best Noise-Cancelling Headphones That Money Can Buy

Now that you’re thoroughly acquainted with the different types of noise-canceling technologies that exist, how they differ, and how they operate, let’s delve into a few of the best ANC headphones that are currently on the market.

Sony WF-1000XM3

A tiny set of true wireless earbuds packing phenomenal active noise-canceling technology, Sony’s WF-1000XM3 is a cutting-edge model that boasts industry-leading ANC tech thanks to a complex algorithm and the use of Sony’s proprietary HD QN1e noise-canceling processor and 24bit audio signal processing. Lithium polymer batteries give the earbuds six hours of juice and offer a total of 24 hours of battery life with the charging case, though a quick ten-minute charge is enough to yield up to 90 minutes of additional music playback time. The WF-1000XM3 also features intuitive external tap and swipe-style touch controls, hands-free smart assistant compatibility, and a Smart Listening function that can automatically detect its surroundings and then switch itself to Ambient Sound mode—one of several proprietary modes alongside Quick Attention Mode–as needed.

Purchase: $178

Bose Noise Canceling 700

Bose has arguably been the single most instrumental and influential force in shaping today’s ANC technology, and unsurprisingly it remains at the forefront of this space with next-level offerings like the plainly-named Noise Canceling 700. Outfitted with 20-hour battery life and voice-activated functionality, these travel-friendly headphones come with powerful active noise-canceling capabilities with 11 different levels of ANC adjustment. A stainless steel headband makes for a lightweight yet durable pair of headphones, while ergonomically-shaped, specially-angled, cushioned leather ear cups allow for all-day comfort. The Noise Canceling 700 is also revered for its absolutely stellar built-in, noise-rejecting microphones that allow for incredibly crisp and clear calls, as well as accurate hands-free controlling. And, in addition to boasting the aforementioned Conversation Mode, these headphones are also compatible with the Bose AR *augmented reality) experience.

Purchase: $379

B&O Beoplay H95

This year Bang & Olufsen celebrated its 95th anniversary, and to mark the illustrious occasion, the elite Danish electronics outfit unveiled the Beoplay H95 wireless ANC headphones. Taking lessons from the rest of the brand’s exclusive flagship headphone models, the Beoplay H95 features a finely crafted polished aluminum frame and headband paired with aluminum control dials and magnetically detachable oval ductile memory foam earpads upholstered in soft top grain lambskin and cowhide leather. And, while the sleek Scandinavian industrial design—which was penned by MNML—is obviously a major selling point on the Beoplay H95, what really separates these top-shelf headphones from other items on the market is its genuine audiophile-grade sound quality, coming from dual, custom-tuned 40mm electro-dynamic titanium construction drivers with neodymium magnets. Other highlights include a folding design and included carrying case and an ultra-potent 1,110mAh battery than can operate for up to 38 hours while utilizing active noise-canceling — or up to 50 hours without it.

Purchase: $899

The 15 Best Noise-Cancelling Headphones

Interested in checking out a broader range of modern headphones with industry-leading ANC tech? Then be sure to check out our guide to the best noise-canceling headphones for over a dozen fantastic on, over, and in-ear options built to help you drown out your surroundings.

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