How do headphones work without batteries

Noise-canceling: anti-noise in the headphones

Do you use your headphones on the go? Then you probably know the problem: If the ambient volume increases, you also have to adjust the volume. This can often drown out street noise and engine noises. Turning louder also means that you put more strain on your ears. In the long run this can become uncomfortable. For some years now, so-called noise-canceling headphones have been offered more and more.

Noise isolating headphones - the passive method

The term noise-isolating headphones also appears again and again in this context. However, these are two completely different techniques. While real noise-canceling headphones can actually eliminate ambient noise with the help of a computer chip, the noise-isolating headphones only isolate the listener from the noise of the environment. Such isolating headphones have been on the market for a long time. This technology works particularly well with the popular in-ear headphones, as they are usually inserted directly into the ear canal and thus function like a kind of earplug with a loudspeaker. The prerequisite for this: they have to fit very precisely in your own ear.

Our in-ear headphones therefore always come with several attachments in the scope of delivery. So there is the right size for every ear. Other manufacturers even offer custom-made high-end in-ears at. These then cost 10 to 20 times as much, but in terms of fit they represent the absolute top in this area. They are mainly used in the professional sector, for example by musicians or sound engineers. But also especially audiophile music fans appreciate such custom-made headphones.

Noise isolating headphones are not only available as in-ears, but also as closed headphones. Some models can reduce the ambient noise considerably. However, manufacturers often compromise between comfort and volume suppression, as many models are either uncomfortable to wear over the long term or do not provide adequate insulation. The ambient noise can be a nuisance, especially when traveling by train or on longer flights. The headphones then stay in or on the ears for longer than an hour or two. This is exactly where modern noise-canceling headphones come in, which actually largely block out ambient noise.

Noise-canceling headphones - actively suppressing ambient noise

This type of headphone is also called Active noise canceling headphones or ANC headphones for short. Active because here a small computer uses microphones to perceive outside noises that hit the headphones and pass them through Anti-noise eliminated.

What is anti-noise?

The term anti-noise may initially be reminiscent of antimatter, CERN and atoms. But it is not that complicated: Behind anti-noise is the knowledge that two tones or sound waves with the same frequency and deflection largely cancel each other out when they meet. For this to work, they have to meet polarized, i.e. shifted by exactly 180 degrees in phase.

So anti-sound is something like an opposing sound wave that can almost completely neutralize the original sound wave. This also happens, for example, with the double bass arrangement in the home theater.

Active noise suppression using anti-noise was first patented in 1933. The physicist Paul Lueg described a process that noise with sound waves opposite phase position suppressed. However, it took decades before it was also used in headphones: In the 1980s, the first ANC headphones were developed to protect aircraft and helicopter pilots from noise.

How do noise canceling headphones use the anti-noise effect?

Imagine a passing car emits a sound wave with the value +1. The microphone in your noise-canceling headphones detects this sound wave. The computer in the headphones calculates the anti-sound wave with the value -1 and passes it on to you. Together, both sound waves result in the value 0 and you don't notice (almost) anything of the unwanted noise. Cabaret artist Vince Ebert explains this a little more “simply” via video:

How do ANC headphones convert sound?

What sounds comparatively simple in theory, requires a lot of effort in practice. The microphones built into the ANC headphones must Pitch and amplitude of the outside noise many hundreds or even thousands of times per second. On the basis of this data, the control electronics adaptively generate the anti-phase sound so that the sound waves cancel each other out in the immediate vicinity of the ear.

For the reproduction of the anti-noise it is crucial that the housing dampens the outside noise before it reaches the ear. Finally, ANC headphones are usually designed as on- or over-ear headphones. Because sound travels through the air at 340 meters per second, processors guide them Arithmetic operation in fractions of a second out. All of this is only possible thanks to powerful processors and very precise sound transducers. An additional rechargeable battery or a battery is required to operate the microphone.

ANC headphones: more than just music on your ears

ANC headphones can block noise whether you are listening to music or not. This also makes them an excellent tool to relax or to concentrate better. A large part of the noise is either kept away or significantly reduced - it is not (yet) possible to really keep all noise away from the ear. Basically, ANC low and medium frequencies much better isolated than high-frequency tones.

Noise-canceling headphones are a real boon for frequent travelers. They relieve the ears because the outside world does not have to be drowned out. There are already some noise-canceling headphones on the market, but the selection is still quite small. In addition, the highly complex technology does not work equally well with every manufacturer to work. Some models suppress background noise well, others less well. The technology is still in the development phase. This applies at least to the consumer sector, because pilots have been using noise-canceling headphones (or headsets) for a long time, as described above. In the cockpit of an aircraft, however, there is usually such a high level of noise that communication would hardly be possible without such equipment.

Noise-canceling headphones have a battery or rechargeable battery that powers the integrated computer. Although the headphones are mostly wired, the battery can of course discharge on the go. When the battery is empty, the noise canceling no longer works, but the normal headphone function is retained. In addition, the small computer that takes on the ANC function has to find space somewhere. This is not a problem with large, closed headphones, as the ANC computer in the earpiece can be obstructed. In the case of in-ear headphones, however, it is usually located on the headphone cable, similar to a somewhat larger cable remote control.

Noise-canceling headphones vs. noise-isolating headphones

One could assume that computer-controlled noise-canceling headphones do more than noise-isolating headphones that do without computer technology. But it is not that simple. After all, ANC technology has only recently been on the market and is still in development. Noise isolating headphones are currently achieving - at least partially - similar results and get by without a battery or complicated technology.

In this article on the American tech website Cnet.com, author Steve Guttenberg describes his experience with both systems. He comes to the conclusion that both technologies serve their purpose and neither of the two variants can currently be called the clear winner. Guttenberg is also impressed by modern noise-canceling headphones, but notes at the same time that they may be more suitable at home without the ANC function. Here, too, manufacturers should compromise between HiFi and volume suppression.

Tip: Hybrid ANC technology is an alternative to noise-canceling and noise-isolation headphones. Of course, we also have helpful tips and information for you in this regard. Just follow the link!

Noise-canceling headphones from Teufel

  • ▶ REAL Blue NC: Simply fade out everyday life with care. Don't let the street noise or the crowds tear you away from your listening experience, just enjoy your sound - no matter where you are.

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Conclusion

  • Noise-canceling headphones show what is possible in terms of ambient noise suppression.
  • They are particularly suitable for frequent flyers and people who primarily use their headphones on the go.
  • You will find high-quality noise-canceling headphones in the Teufel range.
  • Noise isolating headphones also serve their purpose and are sometimes a little easier to use due to the lack of computer technology.
  • Conventional headphones without special ambient noise suppression are ideal as high-end headphones for use at home and offer a good balance between price and sound quality.