Hello!
Interested in portable audio technology, most of us once come across the concept of active noise cancellation. Devices with this system are significantly more expensive and are not produced by all companies. Is it really such a secret and a secret with seven seals that only the initiated know about it?
I suggest trying to figure it out.
A bit of history
It may seem that such a technology should have appeared relatively recently. At least in the 21st century. However, reality can often surprise. The first patent for a noise management system was issued in the United States to inventor Paul Lueg back in 1934.
However, this system got into consumer electronics much later.
Since the 50s of the last century, the active noise cancellation system has been used in highly specialized areas. For example, in aviation.
In 1957, Willard Meeker developed a circuit that, with its compact size (placed in on-ear headphones), made it possible to cut off noise in the audio range from 50 to 500 Hz with a maximum attenuation of about 20 dB.
Willard Franklin Meeker
Bose is considered the pioneer of production of serial models of headphones with active noise canceling system, which in the late 80s of the 20th century introduced the first production model of headphones with active noise canceling system.
However. despite the serial production, there was no talk of a mass sale. The buyers of the headphones were airlines that wanted to provide pilots with protection from the external noise of aircraft and helicopter engines, which made it possible to comfortably negotiate. However, by 1989, Bose had adapted the technology for the masses.
How it works?
In fact, there is nothing difficult in the work of noise reduction. Active noise cancellation systems are based on a wave interference process.
In other words, if you create a specular reflection of the sound wave (invert), and superimpose it on the original, then the sound waves will extinguish each other.
For capturing ambient sound, active noise canceling (ASP) headphones are equipped with one or more microphones that listen to ambient sounds. Then, these sounds are transmitted to the electronic unit, in which they are analyzed and inverted. The resulting mirror wave (phase reversed) is then fed to the speaker. These sound waves in the process of interference mix into a new wave and suppress each other.
These systems are most effective at correcting noise from 100 Hz to 1 kHz.
The main design limitation of such systems is the need for an additional electronic unit, with a separate power supply, which processes external sounds and creates a signal in antiphase. In the case of on-ear and monitor headphones, this is not a problem, since the design of the latter allows you to place the filling and the power source inside the earcup.
The 'earbuds' and 'plugs' require a separate unit on the outside, which no longer looks so aesthetically pleasing.
However, there is another option – placing all the necessary electronics inside the playback device. This is the approach most often used by Sony. A limitation of this type is that both the 'player' and 'headphones' must be compatible and have the necessary components. An example is the Sony Z2 smartphone bundled with Mdr-nc31em headphones
In this case, all the electronic filling that processes external noise is inside the phone. Headphones also have additional microphones, and are equipped with an additional slip ring on the plug.
Many companies, both eminent and not so, are engaged in the production of headphones with ASP.
At the moment, we can state that the famous ones do it better, since in addition to the quality of hardware, such as portable microphones, batteries, and signal processors, the quality of the software that processes the signal is no less important. And the development of high-quality software can only be afforded by companies with a sufficient material and technical base and a staff of professionals in this field.
However, taking into account the reduction in the cost of components, miniaturization of components and the increase in the availability of technologies, more and more companies are starting to produce their audio devices equipped with ASP. Maybe a competitor to Bose has already appeared somewhere.
Is everything so cloudless?
Unfortunately no. Noise cancellation systems are not suitable for everyone. There is a certain percentage of people who cannot use such systems due to the peculiarities of the vestibular apparatus.
How, without trying such systems, to understand whether they suit you or not?
For example, if you are susceptible to motion sickness, then the active noise canceling system is more likely to give you a headache. This happens due to the inconsistency of information entering the brain from different sources. When you are in the ship's cabin, the brain, analyzing the picture, thinks that the body is at rest, and the vestibular apparatus is sending opposite signals. When SAS works, it seems to the brain that we are in a quiet place, but information coming from other senses contradicts hearing. Overstrain of the brain occurs, and as a result, headache.
In addition, you should not forget that in order to suppress noise, the system produces anti-noise. And if we manage to deceive the rumor. the nervous system cannot be fooled.
How to be?
Despite the 'such dire' negative consequences, do not despair. The percentage of people who have ASP causes headache or nausea is not that great. According to research, this is only 5-6% of the total mass. Despite this, before buying, I highly recommend listening to headphones equipped with SAS for at least 1.5-2 hours. It is usually during this time that side effects appear, if any for you.
I would like to hear your experience of using headphones with ASP, if any. And if you didn't have that experience, would you like to try active noise canceling headphones?