WHAT IS ACTIVE NOISE CANCELLING?
Whether you’re on the train, sitting in a coffee bar or lounging in the library, headphones are an unbeatable way of enjoying music or listening to an audio book. In-ear models or over-ear, closed-back headphones are best suited to keeping out ambient noise.
But anyone looking for absolute peace and quiet, whether it’s on a long-haul flight, at the office or elsewhere, should opt for Active Noise Cancelling (ANC). This technology is able to block out disruptive ambient noise almost entirely. In this article, we explain how it works.
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Active Noise Cancelling – what is it?
Expressed in simple terms, sound waves are created by the vibration of molecules in the air. The volume and frequency of a noise is graphically represented by engineers in a waveform. When a sound wave is superimposed with a precise replica that has a 180 degree shift in phase, they cancel each other out. As an analogy, just imagine a pendulum that is set in motion from both sides using precisely the same amount of force – it won’t move a single millimetre!
This “anti-noise” effect was first patented in 1933 by the German physicist Paul Lueg. In connection with headphones, this technology is called “Active Noise Cancelling”, and the principle described above is used to actively suppress ambient noise so that only the desired sound waves, such as music or speech, are registered by the ear. It can also be used, of course, to create absolute peace and quiet for the purposes of relaxation or concentration.
How does Active Noise Cancelling work?
Microphones built into the ANC headphones continuously record external noise. The powerful electronics inside the headphones then generate the appropriate anti-noise in real time. The structural and sound properties of the headphones also need to be taken into account during this process, and unwanted noises and their inverted (antiphase) version only cancel each other out when everything is perfectly coordinated.
Instead of whining aeroplane engines, humming air-conditioners or disruptive traffic noise, you get perfect tranquillity or soothing music. But ANC headphones are not only the perfect companion for travellers, they’re also ideal in everyday working life: making it much easier to concentrate in open-plan offices, for example.
Do ANC headphones sound as good as regular models?
Although the “anti-noise” strategy sounds easy enough in principle, actually implementing it in a set of headphones is extremely complex. The noise needs to be perfectly captured by the integrated microphones, and then analysed by the circuitry within a matter of milliseconds. And the transducers need to operate with incredible precision. At the same time, when listening to music on the headphones, the sound waves need to arrive at the ear drum without any distortions and at full volume. Engineers need to take a number of aspects into account:
- Which design will the headphones have? On-ear, over-ear or in-ear?
- Where will the microphones be located?
- How fast are the digital signal processors?
- How much power does the circuitry need?
- Which sound properties do the headphones have? Small details can have a huge impact
The first ANC headphones managed decent noise cancellation, but their sound quality left a lot to be desired. But modern headphones with high-performance drivers can certainly keep up in terms of sound quality. The AVENTHO 300 wireless over-ear headphones feature the tried-and-tested, high-performance STELLAR.45 driver from our studio headphones for an unrivalled sound experience.
Which ANC variants are there?
Feedforward ANC
With feedforward ANC, the microphone is placed outside the earcup. This means that noise can be picked up early and suppressed. However, these microphones are susceptible to wind.
The circuitry needs to include the sound-isolating properties of the headphones as well as their wearing method and design in its complex processing calculations. The complicated part: These factors interact differently depending on the person, for example due to the different geometries of the outer ear, and also depending on the way the headphones are worn. This can be remedied by adaptive algorithms that adjust in real time, such as in our AVENTHO 300, although these require additional energy.
Feedback ANC
In the feedback ANC set-up, the microphones are located inside the earcup. They pick up the remaining ambient noise that hasn’t been blocked out by the isolating properties of the headphones and cannot be cancelled out by the feedforward ANC. The advantage of feedback technology is that it is quite resilient to the aforementioned individual differences in the geometries of the outer ear or the wearing situation.
The term feedback refers to the fact that the microphone in the earphones constantly monitors the sounds and makes adjustments to optimise noise cancellation.
Hybrid ANC
The hybrid technology combines the best of both worlds. Here, microphones are integrated into both the outside and inside of the headphones (feedforward and feedback microphones). This has the advantage that noise is detected as quickly as with the feedforward design and is optimally supported by the feedback technology. Both microphones send the recorded sounds to a digital signal processor, which analyses the information and generates a suitable anti-noise. This is then played back to reduce the unwanted noise. The digital signal processor has to work extremely quickly. A small example: If the feedforward microphones are approx. 2 cm away from the driver, the digital signal processor including microphone, A/D converter, D/A converter and driver only has approx. 60 microseconds to play back the out-of-phase signal.
We therefore use state-of-the-art processors, top-class components and the know-how of our engineers to ensure an optimum fusion of Active Noise Cancelling and excellent sound.
Transparency mode – reverse ANC mode
In contrast to ANC, where external noise is reduced to a minimum, transparency mode is designed to specifically blend in outside noises as well as your own voice so that you no longer even notice that you are wearing the headphones. The headphones should basically be acoustically “transparent”. In principle, the same hurdles apply here as with ANC. In other words, the system has very little time to play back the appropriate signals. Transparency mode has a few special features. As soon as the environment is blended in again, the wearer is communicating again with their surroundings. The resulting occlusion effect can be particularly disturbing. As soon as you put on closed headphones and start talking, your voice sounds unnatural and muffled. Our engineers specifically utilise feedback technology here to reduce the occlusion effect. This is complemented by feedforward technology, which focuses on the natural reproduction of external sounds. So here too, hybrid transparency mode utilises the best of both worlds.
ANC headphones from beyerdynamic
Our ANC headphones deliver superb sound, whether ANC is activated or not. Depending on your personal preference, you can choose whether in-ear or over-ear headphones with ANC suit you better.
Over Ear: AVENTHO 300
Our AVENTHO 300, a wireless over-ear headphone with ANC, Dolby Atmos and head tracking, impresses with legendary beyerdynamic sound with the STELLAR.45 transducers manufactured in Germany. With the AVENTHO 300, you can immerse yourself in your music without disturbing background noise. AVENTHO 300 eliminates background noise to a minimum thanks to powerful adaptive ANC.
Hybrid transparency mode enables the perfect combination of music enjoyment and perception of your surroundings. The integrated microphones also ensure clear conversations and block out background noise when making calls.
In-Ear: AMIRON 300
If you prefer earbuds, the AMIRON 300 is the right choice. These feather-light and ergonomically shaped earbuds are equipped with powerful 10 mm drivers and the latest codecs, ensuring the special beyerdynamic sound and outstanding voice quality.
You decide whether you want to be connected to your surroundings or completely immersed in the music – ANC or transparency mode make both possible. AMIRON 300 is also equipped with an automatic pause and playback function and integrated touch sensors. The six high-quality microphones effectively eliminate distracting ambient noise during phone calls. With a total battery life of up to 38 hours per charging case, you can rely on the headphones. If you’re in a hurry, 10 minutes of charging is enough for a further two hours of use.
Like to know what “True Wireless” is all about? For a concise explanation read our article: What is “True Wireless”?