Active noise cancellation in headphones and why it gives you headaches. Audio-Technica ANC7b - total immersion
Noise for residents of megacities is everywhere. Conversations, the hum of machines, construction tools and equipment, ringing mobile phones, sounds of animals - all this not only pollutes the general background, but sometimes puts psychological pressure on a person.
For example, you are going on a trip or a business trip, but in the transport a baby is crying angrily, a dog is barking, or someone, not really considering those around him, allows himself to speak out about everything that comes to his mind, and even in a raised voice.
If you want to drown out the whining of a crying child, “turn off” other unwanted sounds from your perception, then you will need good headphones. “Good” in this context means that they will have the maximum level of noise reduction.
The first thing you need to remember about noise-canceling headphones is the basic way they work: they first block out noise and then let you enjoy yourself. high quality sound.
With that said, here is a list of active noise canceling headphones that deserve your attention and are worth buying. Make your world more harmonious and control background noise with these great headphones.
Best of the best: Bose QuietComfort 35
Acoustic noise-canceling headphones from Bose. Famous brand is a synonym high quality sound and excellent quality. It is not surprising that it was this world-famous company that introduced the world to unique noise-canceling headphones.
Bose's QuietComfort 35 headphones may be too expensive for most people, but they are by far the most comfortable and effective noise-canceling headphones available. They come in classic black or white, but there are other color combinations available.
The headphones fold into a convenient bag for storage or transportation. Sure, they're not cheap, but the noise-canceling technology developed by Bose has been refined over the decades. It remains the pinnacle in this segment of modern technology.
Best Sound: Monoprice Hi-Fi Active Noise-Canceling Headphone
These aren't the cheapest noise-canceling headphones on the market, but they offer the best combination of performance and price. You can find noise-reducing headphones for as little as 300 rubles, but they are unlikely to work as advertised.
The Monoprice Hi-Fi headphones promise excellent noise-canceling performance. Active noise-canceling technology blocks up to 22dB of ambient noise and runs on AAA batteries, promising up to 50 hours of use.
It is equipped with a three-pin remote control remote control, which allows you to use them with a mobile device or applications. The design itself is pretty boring. There is no Bluetooth compatibility, but when it comes to their main function, in the noise canceling category, these headphones are flawless.
Extend the fun: Bose QuietControl 30
As mentioned, when it comes to noise-canceling technology, Bose is the unrivaled leader. Simply because the company has been working with sound since the 1980s, has vast experience and a lot of proven and new technologies. The company was separately engaged in the development of special equipment for noise reduction.
It is thanks to Bose that we can use the best headphones with optimal noise-canceling properties. But the QuietControl 30 headphones offer more than just performance, reliability and style.
These in-ear headphones provide a high level of comfort. Some people find in-ear headphones generally uncomfortable to use for long periods of time, so for those users, we recommend the QuietComfort 35. They're so comfortable that you won't even feel them. In any case, there will be no discomfort. Even if you use them for long period time.
Best Comfort: Sennheiser PXC 480
When it comes to comfort, the most comfortable headphone design is an over-ear design. These headphones cover the entire ear, extending slightly beyond the shell area, which prevents the pressure that those who wear headphones directly on or inside their ears may experience.
These ear devices are equipped with soft materials that provide additional comfort while reducing noise levels. Durable, durable materials give active noise-cancelling headphones durability and reliability. They also have a unique TalkThrough feature that allows users to communicate without removing the headphones.
Stylish: wireless BOHM Bluetooth
These are fairly small headphones that are affordable for almost everyone. Unlike many other noise-canceling headphones, BOHMs include a rechargeable lithium-ion battery that allows you to enjoy up to 18 hours of sound.
From two high quality stereo speakers you can expect high quality sound with strong bass. As additional bonus The headphones are Bluetooth compatible, meaning you don't need wires. The active headphones are available in two equally stylish color tones, but we recommend a brown or gold option for maximum wow factor.
In addition to great features, BOHM headphones offer you amazing comfort. They are equipped with lightweight leather ear cups and a soft headband. There's even an in-line remote control and microphone that allows you to make hassle-free calls on the go. Stress-free listening to music is guaranteed.
Best Sound: V-MODA Crossfade Wireless Over-Ear Headphones
Demon wired headphones V-MODA Crossfade looks like something out of science fiction. The two-tone industrial style will make you look like a DJ from the future. But they're not just stylish.
They sound great. These headphones have a dual diaphragm 50mm driver that delivers crystal clear sound that separates the bass from the mids and high frequencies melodies.
These headphones will allow you to connect to a wired or wireless network depending on your circumstances. Let's say you have a smartphone without a connector and need wireless headphones, but you're using wired headphones with your work laptop. V-MODA Crossfade can handle both devices, and you'll be able to sync the headphones to two devices at once if you're using your phone and tablet at the same time.
These headphones can stream music wirelessly for about 12 hours on a single charge. But you can still use them wired if the battery dies. The headphones are available in black, chrome, red, and white colors.
Boost Sound: Paww WaveSound 3 Bluetooth
WaveSound 3 headphones are designed primarily for travel. They are equipped with a travel case and special structural elements designed for airplane flights or train travel.
They include an aircraft adapter designed to connect to certain in-flight surveillance systems. They block out cabin noise, eliminating up to 23 dB of unwanted outside noise. In addition to clear sound reproduction and noise cancellation, WaveSound 3 has a built-in microphone for calls (please don't do this on a plane!).
The lightweight and durable metal design will fit comfortably on your head. Sound connoisseurs say the WaveSound 3 headphones do a great job of canceling out noise, delivering great sound to their favorite songs, especially when traveling by train.
Best Design: AKG N60 Headphones
Portable, lightweight and attractive design AKG headphones The N60 is ideal for those on the go. Thanks to 30 hours battery life And USB charging This device will appeal to those who do not sit still.
The AKG N60 is made of plastic wrapped in high-quality leather that extends to the ears. Active noise cancellation is present, but the real appeal of these headphones is the sophisticated design. The audio highs have very clear mids, and the lows have great depth and detailed bass.
Bottom line
All of these models offer varying degrees of noise reduction, but always offer ideal sound and user comfort. Choose your type of headphones, download great songs, and fill your world with your sound.
Today's market is represented by thousands of headphone models: from cheap Chinese NoName earplugs to exclusive Final Audio Design, costing more $8 000 . Prices are driven by customer needs and technology. Today we will talk about the active noise reduction technology installed in most closed-type headphones, and most importantly, we will find out the causes of headaches when listening to such “ears” for a long time.
Active noise reduction system. History and operating principle
Music has long become man's most reliable companion. For any mood, state, emotions and experiences there is always a melody that can warm your soul, heart and thoughts. Manufacturers started thinking about portable music back in the middle of the last century. In 1979 the company Sony introduced the first portable cassette player Walkman TPS-L2. Several decades later, this development was recognized as one of the company's greatest inventions. In 1984, the Japanese manufacturer, keeping up with the times, released the first CD player Sony Discman D50. In the summer of 1998, the first MP3 player burst onto the market - MPMan F10, with a capacity of 32 MB. And all this time, the evolution of players was accompanied by the development of guarantors of quality and good sound– headphones.
The history of the development of the active noise reduction system (hereinafter - SAS) begins in the distant 1934 when the inventor Paul Luge receives a patent describing the principle of canceling sinusoidal signals emitted by a loudspeaker. In 1950 Lawrence Vogel pioneers the use of noise suppression systems in helicopter cockpits and aircraft cabins.
I got to SAS headphones back in 1957 year when Willard Meeker on the presented working model of on-ear headphones, I was able to cut off noise in the audio range from 50 to 500 Hz. The first one production model headphones with active noise reduction system was presented by the company Bose in the late 80s and was used in aviation.
Bose Quiet Comfort: the beginning
The operating principle of SAS, from a physics point of view, is very simple. Any sound is represented by a wave, which means you can create it mirror reflection– an inverted wave that completely cancels out the original one.
The headphones, equipped with an active noise reduction system, contain microphones. Their task is to measure the level of ambient noise. The sound signal received from the outside is converted into an inverted wave and transmitted to the main speaker. The new wave is active in antiphase(minus the useful signal - music) to noise and, thus, reduces its sound to zero.
Headache
It would seem that the use of active noise suppression technology should significantly improve the life of avid music lovers who cannot imagine going to work, walking or active recreation without on-ear headphones wrapped around their heads, musical drive and rhythm. The number of models equipped with SAS is valid. There are a wide variety of headphones on the market. price categories and form factors: from inexpensive compact plugs to heavy studio monitors. The noise reduction system is improving every day, the quality of music playback is increasing, manufacturers are finding new and new marketing solutions to popularize headphones with the system Noise Canceling. But there is a category of people who, despite all their positive attitude towards portable sound, are forced to abandon all the technological advantages of “perfect headphones” for one simple reason - intolerance to the active noise cancellation system.
The realities of today's market are significantly different from those of just 10-15 years ago. Before going to the store, the buyer carefully studies the reviews, reviews and re-reads a dozen or two reviews, and only then decides to buy.
Among the reviews dedicated to the category of headphones with active system noise reduction from famous brands such as Sony, you will find many positive points. Yes, the manufacturers have really done a lot to ensure that the headphones not only sound good, but also fit comfortably and are different. interesting design. Read the lines more carefully and you will see that a small percentage of happy owners complain of constant headaches and nausea when wearing headphones with ASP. What are these – customized reviews from competing parties or a reality that not everyone faces? So why do you get a headache when using seemingly perfect headphones that allow you to enjoy crystal clear sound without extraneous noise?
Reason one: when the sea is rough.
If at least once in your life you have had to experience all the bitterness of a deplorable condition, which is accompanied by seasickness, I hasten to upset you. You may be in the unlucky category 5-7% people for whom headphones with active noise cancellation will remain a useless technological breakthrough.
Seasickness and headaches caused by ASP headphones have a lot in common. At the moment when a person is calmly resting in a ship’s cabin, the brain understands that the body is at rest. At the same time, the ship is constantly rocking on the waves and this movement is captured by our internal accelerometer - vestibular apparatus. The endolymph moving in the ear canal irritates the nerve endings, which send an impulse to the brain, making it clear that the body is in a state of movement. But you are reclining in an armchair in a cozy cabin!
By putting on headphones with active noise cancellation and going outside, you are, without realizing it, deceiving your brain. Passers-by coming towards you, a noisy highway, the hum of wheels, a sharp wind - the organs of vision clearly paint a picture of the fact that you are on the street. But the hearing organs indicate complete silence. This discrepancy confuses the brain. Alas, a headache is guaranteed.
Reason two: monotonous stimulus.
Having understood how active noise cancellation works, Grandpa Newton would have said the following: “Force is counterforced.” Such a sound battle and interference process as a result, it achieves the desired result - we eliminate unnecessary ambient noise and can completely immerse ourselves in the music.
There is just one “but”. As a result of this constant noise jamming, monotonous sound waves act on the eardrums. This does not mean that we should hear a hum or any extraneous noise. The brain perceives exclusively the variety of sound tonics of a particular audio recording or track, but the nervous system... The action of such vibrations is the principle that works at the basis of the active noise reduction system and, alas, it is impossible to predict which organism it will lead to nausea and headaches.
Reason three: silence is not always calm.
In research institutes and laboratories involved in the study of sound and sound waves, there are so-called “absolutely quiet rooms”. They are designed in such a way that they can block up to 99,9% all noise. It is in such premises that high-quality and expensive products are tested. sound equipment world famous brands.
Imagine that you find yourself in such a room. After a few seconds, you will begin to hear the squeak of a mosquito. A few minutes later - a rumbling stomach and a pounding heart. Five minutes of being in absolute silence will begin to create a state of anxiety and excitement in the body. Not a single person could stand more than 45 minutes in such a room.
Despite the fact that when listening to music on headphones with an active noise reduction system, absolute silence is out of the question, the very principle of operation of the ASH intersects with that very “absolutely quiet room”. People whose bodies are not adapted to this type of headphones will experience headaches and nausea through 1.5 – 2 hours operation.
Reason four: bass is my enemy
Depending on the height, all sound frequencies during equalization are usually divided into: high, medium and low. Active Noise Cancellation works best with clipping low frequencies, which predominantly saturates the street noise around us. The situation is worst with high frequencies, since there is a risk of suppressing the useful sound signal represented by the music.
Mirror sound wave, reproduced in antiphase in order to suppress ambient noise, is most saturated precisely low frequencies. Low frequencies cause maximum vibrations when exposed to liquid, and if we take into account the fact that the human vestibular apparatus is filled endolymph, That constant vibrations from booming bass and cause headaches.
Reason five: design flaw
Another reason why the owner of headphones with an active noise reduction system may constantly experience headaches is that the headband is too tight. However, this a common problem on-ear headphones and SAS itself can hardly be blamed for this.
The design feature of any on-ear headphones is an elastic headband that should hold them on the head. Constant pressure on the temporal zone leads to increased pressure. After a few hours of using such “tight” headphones, headaches and nausea occur.
How to avoid useless purchases
Of course, headphones equipped with an active noise reduction system have a number of advantages: comfort when listening to music, a high level of sound detail and a safe volume level. Alas, it is impossible to predict exactly how your body will react to SAS. Before you give away your hard-earned money, and then, literally, do not complain about the headache, try to borrow headphones equipped with ASP from friends or acquaintances. Remember, to understand whether SAS really has a negative effect on your condition, you need to listen to headphones for more than 2-2.5 hours.
Having bought the model of headphones you like, which is called “without looking”, according to Article 502 Civil Code of the Russian Federation and article 25 Law of the Russian Federation of February 7, 1992 No. 2300-1 “On the Protection of Consumer Rights”, you have 14 days to return goods that do not fit “in style, color or dimensions”, subject to all storage conditions. To avoid disagreements and refusals to return, before purchasing, re-read the above articles and consult with a consultant at a particular store.
4.75 out of 5, rated: 8 )
Airlines typically provide business class passengers with a “welcome kit,” which includes earplugs. Indeed, the monotonous hum of powerful aircraft engines can be unbearable; it prevents you from falling asleep or enjoying your favorite music. No plug headphones (or even closed ones) can cope with it - passive noise isolation does not do a very good job of preventing the spread of low-frequency sound that is characteristic of both airplanes and other modes of transport. But headphones with active noise cancellation can come to the rescue.
Bring down the noise
The principle of active noise cancellation itself has been known since the 1930s, but the first working prototypes, intended for airplane and helicopter pilots, appeared in the late 1950s. True, they turned out to be too cumbersome and were not widespread. Only at the end of the 1980s, when the sizes electronic components became small enough, Bose made the first practical headphones with active noise cancellation.The idea behind active noise cancellation is quite simple. Sound is a wave of rarefaction and compaction, and where there is a wave, interference can be used. By creating an inverted wave (exactly out of phase) in the right point(in the ear, as close to the ear canal as possible) and at the right time, you can completely extinguish the original one. This is exactly how the active noise reduction system works: there are microphones inside the headphones that measure the level background noise. This signal is inverted and transmitted to the speaker, which ensures the appearance of a wave in antiphase to the noise (when playing music, you also need to take into account the “useful signal” - subtract it from the measured noise).
The main problem with active noise reduction systems is related to inaccurate phase matching. Even a small phase shift results in serious distortion. Therefore, active noise reduction works well with monotonous and low-frequency noise (the wavelength of low-frequency sound is long, and therefore the phase difference is small) and poorly with high-frequency and sharp irregular noises - screams, speech, music. The latter have to be dealt with using passive noise insulation. Often in headphones with active noise reduction you can hear a quiet hiss - this is precisely a consequence of the inaccuracy of the phase shift of high-frequency noise.
No confusion
The creators of headphones with active noise cancellation also sought to get rid of the ever-tangling and inconvenient wires. All these devices work on Bluetooth protocol, which allows you not only to transmit high-quality stereo sound (although, of course, audiophiles will not agree with this) using the A2DP profile (Advanced Audio Distribution Profile) and the new improved AAC and AptX codecs, but also to control the player of a mobile device (for this, the AVRCP profile is used ( Audio/Video Remote Control Profile).Headphones are both wireless headsets, supporting Hands-Free Profile (HFP) and Headset Profile (HSP), which allows you to make and receive calls when connected to smartphones. You just need to take into account that noise reduction only works in one direction, that is, your interlocutor will hear all the noise around you. By the way, all the headsets in our test are equipped with NFC identification, so connecting them to mobile devices that support this technology is very simple - just touch the point with the NFC icon on the headphones with the same smartphone.And all wireless headphones are equipped with wires - according to airline rules, use wireless devices prohibited during the flight. Just plug the wire into the corresponding headphone jack, and Bluetooth will turn off automatically. In addition, most models, even when the batteries are completely discharged, continue to work like regular wired headphones.
How we tested
A Samsung smartphone was used for the test Galaxy Note 3 (SM-N900). Sound processing in headphones (equalizer, effects) was forcibly disabled using proprietary utilities or control keys. The player was set to the Flat equalizer profile. The headphones were tested in wireless and wired modes. Operating time is based on wireless music listening with noise reduction enabled.Nokia Purity Pro by Monster (BH-940)
Bluetooth: Ver. 3.0 NFC: yes Operating time: 24 hours Noise reduction: 6/10Ergonomics? When unfolded they turn on automatically. Sensors turn on noise canceling as soon as you put the headphones on and automatically turn them off a few minutes after you take them off. Controls - mechanical buttons. In general, apart from the small size of the buttons, the headphones did not cause any complaints; everything is quite convenient. For wire connection, a standard 3.5 mm three-pin connector is used.
Sound I would like to call the sound spectacular: the bass is elastic and intelligible, the drums are biting, like a slap in the face, the voices are clear, without distortion. Increasing the volume does not cause distortion. Unfortunately, all this works only while the headphones are connected to the player by wire. When playing via Bluetooth, interference appears, and the crystal brightness gives way to a primitive “blurredness”. A good compromise is a wire for home, Bluetooth for a noisy street.
Pros: comfortable ergonomics; excellent sound over the wire; long battery life
Minuses: lack of a proprietary application for management and configuration; lack of battery charge indication (on a smartphone or headphones); average level of noise reduction
Sennheiser MM 550-X Travel
Bluetooth: Ver. 2.1 NFC: yes Operating time: 8 hours Noise reduction: 5/10Ergonomics This is one of two models in our review that have a dedicated audio pass-through button. When pressed, the speakers switch to transmitting sound from external microphones. The quality of sound transmission in headset mode is frankly poor, since the microphones are too sensitive and transmit even the slightest noise, and they are audible not only to the interlocutor, but also to you (noise reduction does not work).
Sound These headphones have very high quality speakers. For example, cymbals sound more natural on them than on any other, but only if this moment Only the cymbals play. But as soon as the musicians give it a blast, the sound is filled with distortion in such quantities that it becomes difficult to recognize the singer’s voice. It’s a pity, but the headphones from the famous company demonstrate complete impotence when listening to almost any music, both wirelessly and with it.
Pros: good ergonomics; built-in surround sound processor; removable battery
Minuses: poor sound quality (both as headphones and as a headset); lack of a proprietary application for management and configuration
Creative AURVANA Platinum
Bluetooth: Ver. 3.0 NFC: yes Operating time: 12 hours Noise reduction: 8/10Ergonomics The headphones have three noise reduction modes: “Airplane”, “Street” and “Office”, they are switched manually (from other manufacturers - automatically). They are comfortable as a headset, although the microphone placement may not be the best - the interlocutor heard interference from surrounding noise. It's also worth noting that noise cancellation turns on and off independently of the headphones, which can drain your battery quickly.
Sound The developers wanted to transport the listener to an imaginary listening room, secluded, safe, and cozy. Electronics are always involved in sound processing (with or without wires), filling it with a slight reverberation to simulate space. This approach is good for acoustic blues or chamber pieces. Music with a powerful rhythm section is drowned in loud, inaudible bass, “blurred” by reverberation. The sound is interesting, but not for everyone.
Pros: good noise reduction (both passive and active)
Minuses: sound quality is average; buttons are difficult to find; lack of a proprietary application for management and configuration
Sony MDR-ZX750BN
Bluetooth: Ver. 3.0 NFC: yes Operating time: 13 hours Noise reduction: 6/10Ergonomics The ear pads of the headphones are small in size, so it would be more correct to classify them not as closed, but as over-ear. However, they are in no way inferior to their competitors. The control buttons on the bottom end of the headphones are convenient, although they are not always easy to find. The voice quality in headset mode is excellent. Noise reduction has three modes, which turn on automatically after analyzing the surrounding sound environment. You can turn on noise reduction manually, but only in “street” mode.
Sound Wow! With a small-looking driver, these headphones are an uncompromising choice for bass players. The built-in amplifier is configured for powerful, loud, but very intelligible bass. At the same time, high frequencies are reproduced quietly and very carelessly. Sony can be safely recommended to fans of dance music, electronics, hardcore, as well as those who want to memorize the parts of Duff McKagan or Flea. There is no point in connecting a wire - without a built-in amplifier, the headphones are practically powerless.
Pros: good wireless sound; good speech transmission as a headset
Minuses: buttons are difficult to find; lack of a proprietary application for management and configuration
Parrot Zik
Bluetooth: Ver. 2.1 NFC: yes Operating time: 6 hours Noise reduction: 8/10Ergonomics? Philippe Starck design, white leather and gold plating. And the noise reduction level is very good. For control, the manufacturer left two small mechanical buttons recessed into the body - power and noise reduction; other commands are issued using touchpad. It's actually not very convenient. The sensors automatically pause the music when you take off your headphones. When used as a headset, the interlocutor can clearly hear the surrounding noise, despite the many microphones, which, in theory, should neutralize this effect.
Sound The sound of these headphones is tempting to call unnatural. The built-in amplifier, which does not turn off, enhances the highest and lowest frequencies, muffling the mids. This is a long-known way to make the sound a little more cheerful, but a sophisticated listener cannot buy this trick. However, Parrot also has a strong side: it is the only model that is completely free of interference when listening via Bluetooth.
Pros: excellent noise reduction; convenient utility for management and configuration
Minuses: short battery life; average sound quality; uncomfortable touch control
Samsung Level Over
Bluetooth: Ver. 3.0 NFC: yes Operating time: 15 hours Noise reduction: 8/10Ergonomics Two mechanical buttons, power and noise reduction, the rest is controlled using the touch panel, which, in our opinion, is not very convenient due to vulnerability from accidental touch. The model works well as a headset. There is a proprietary utility for managing headphones with many options for customizing and processing sound. For some Samsung smartphones Galaxy available additional features (voice control). By the way, this is the only model in the review that has a hard case included.
Sound This model impresses with its power reserves. She can easily throw a disco even in a subway car. It has a catchy sound, although less honest than Monster. Adding to the fun is the slightly enhanced upper mids, which add punch to the drums. Overall, this is a universal, comfortable, well-protected model for all occasions. There is no point in using a wire; without “safety electronics” the sound of the model is much duller.
Pros: excellent noise reduction; convenient utility for management and configuration; good sound; hard case included
Minuses: inconvenient touch controls
Plantronics Backbeat Pro
Bluetooth: Ver. 4.0 NFC: yes Operating time: 24 hours Noise reduction: 7/10Ergonomics The volume is adjusted using a ring (it’s hard to imagine a more intuitive way). It's hard to miss the control buttons. Sensors automatically pause when you take the headphones off and resume playback when you put them on, gradually increasing the volume. This is the second model in the review that has a dedicated pass-through button. But it works in a very interesting way: the music is not turned off completely, but only muffled, the speakers switch to external microphones, and the quality of sound transmission is very close to “live”.
Sound The element of these headphones is complex arrangements. Enhanced high frequencies enhance the clarity of background instruments. It's interesting to listen to them, the volume reserve is pleasing, although the insufficiently powerful amplifier produces unintelligible, albeit loud, bass. Headphones are suitable for lovers of jazz, blues and classical music. Listening to rock and electronics on them is a bit boring. We did not feel any difference between listening with and without wire.
Pros: excellent ergonomics and controls; good sound; battery charge indication; long battery life
Minuses: A hard case would be nice to have included
A sound wave is a wave of compression and rarefaction of air. If you use speakers to create waves of the same frequency and amplitude, but of opposite phase, they will weaken each other. This is the principle of operation of ANC (Active Noise Control), shown in Figure 1. Active noise reduction is a technology that can significantly reduce noise levels, especially if the sound source is well localized. More top scores ANC indicates if the noise spectrum has periodic components.
The innovative company Promwad is developing embedded, scalable active noise reduction systems for various applications.
Areas of application of ANC systems
- Ventilation
- Quiet server cabinets
- Windows and slopes
- Cars and trucks
Figure 1 - ANC operating principle
Ventilation devices, hoods, compressors
One obvious application for active noise cancellation is ventilation- ventilation devices, hoods, compressors. Mechanical ventilation systems are noisy, which can have a negative impact on people who spend long periods of time in such areas. An example of such a space would be “clean” rooms where people have to work for long hours at a time. The principle of active noise reduction was proposed a long time ago, in 1936 by P. Leug, but then there was no technical feasibility use ANC system in modern understanding, and until recently, the problem of noise from ventilation was solved only by installing sound-absorbing structures, sound screens and various resonators. We are currently developing a scalable ANC system for ventilation.
This audio excerpt shows the result of an ANC system simulation. At first it is turned off, the noise of the fan is clearly audible. Then the system turns on, and the noise weakens - periodic components disappear from the spectrum. In the presented example, passive sound insulation was not modeled, which can further improve the result.
Quiet Server Enclosures
Quiet Server Enclosures- another popular product where the ANC system can be successfully used in conjunction with passive sound insulation means. This symbiosis of the two principles is most effective because noise is attenuated across the entire frequency range: ANC is most effective in the low-frequency region, and passive sound insulation is most effective in the mid- and high-frequency region. Generally speaking, passive sound insulation can be effective in the low frequency range, but the thickness of the soundproofing material must be at least half the wavelength. For example, for a hum with a frequency of 50 Hz, effective noise insulation requires a layer of material about 3 meters thick, which is an unrealistic requirement for a server cabinet. And the ANC system is much more compact, and also does not interfere with the air flow for ventilation of the cabinet contents.
Double-glazed windows and slopes
A promising area of application for ANC is double-glazed windows and slopes. If the house is located near a highway, then constant noise can adversely affect the health of residents. Therefore, our immediate plans include adapting ANC for installation in double-glazed windows and window slopes. The popularity of such windows is difficult to overestimate - it’s worth imagining a summer night when you can’t open the window because of the noise on the street, and you don’t want to sleep with the air conditioner on.
Noise reduction in cars
Development ANC for use in cars, cars and trucks- one of our immediate goals. Noise in a car mainly comes from the noise of the tires on the road surface and is transmitted through the suspension and body. The difficulty in suppression systems lies in the need to position the speakers so that the sound wave from them interferes with the surrounding noise precisely in the areas where people are located. We plan to develop a system both for implementation by large automakers and for customizers.
Specifications:
- Number of compensating speakers: 1-8
- Number of microphones/non-acoustic sensors: 2-16
- Operating frequency range: 20 Hz - 1000 Hz
- Periodic Attenuation Level: 25 dB
Do you want to implement noise reduction technologies in your project?
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The life of a city dweller is full of stress. Therefore, when coming home, every city dweller strives for maximum comfort and silence. But, alas, if comfort is still achievable, then hiding from the noise of the metropolis is not so easy. And, to be honest, many modern high-rise buildings do not have good sound insulation. Many people are familiar with the feeling of “kinship” with their neighbors, which arises from the fact that all the ups and downs of their lives are often heard better than a TV show.
Traditional methods of getting rid of street noise were still considered to be plastic double-glazed windows, and for internal noise insulation - sound insulation of walls, floors and ceilings with special building materials. This applies to this day, but hasn't modern science come up with something else? Let's look at the best innovations for the city in the field of devices for active noise suppression in the apartment.
Radio-electronic jammers
Our musical tastes do not always coincide with the tastes of our neighbors. Loud music or a screaming TV is the bane of many apartment buildings. If one likes it, everyone listens. And if the neighbors are also karaoke fans, the problem becomes even more acute. Alas, unfortunately, these “musical” people do not always adequately respond to requests to “turn it down.” Well, if you can’t come to an “amicable” agreement, and your nerves are already at their limit, you have to accept radical measures And for this it is not necessary to involve law enforcement agencies.
There is a way to fight effectively on your own. To do this, you can use an electronic jammer (in common parlance, a “jammer”).
You can either purchase such a device or make it yourself. On the Internet you can find a lot of diagrams, following which you can make these electronic jammers. The schemes can be either simple or quite complex, but the principle of their operation is essentially the same.
Operating principle of radio frequency suppression device
A device whose task is to silence the work electronic devices, is a signal generator in the same frequency range as the frequencies of the jammed devices, only in antiphase. The signals generated by the device do not carry any information, they are simply “white noise”. Therefore, before purchasing a device, you must first determine the frequency range in which this device operates. The meaning is simple - if the frequencies do not match, the device will not perform its function.
The effect of the “jammer” is as follows: the “useful” signal from the neighbors’ electronic device is replaced by “white noise”, which, in general, is what the user of such a device needs.
After the frequency range, the second important characteristic of a jammer is its range. The distance over which the radio frequency “jammer” effect operates depends on many factors: where the device is used - outdoors or indoors, what the weather is like, etc.
Jamming electronic devices is not a myth.
But it should be remembered that the use of “jammers” is illegal, so they must be used with caution and should never be abused.
A similar device for suppressing noise in an apartment can be purchased in various online stores. The price ranges from several thousand to several tens of thousands of rubles (depending on the power of the device and the range of frequencies covered).
Noise suppression device in the Sono apartment
This system was developed by the Austrian industrial designer Rudolf Stefanich. It is based on the same technology that is used in headphones. This small device It is attached to the window using special suction cups and absorbs most of the extraneous sounds coming from the street.
The device kit consists of a microphone, speaker and built-in processor. A speaker pressed against the glass uses it as a resonator and reproduces sounds in antiphase.
The built-in processor analyzes and filters sounds received through the microphone. This technology allows the device to selectively suppress noise based on user settings.
Why is this necessary? Very simple. You can, for example, block out the noise of cars and utility vehicles, but set the device to allow the sounds of chirping birds and rustling leaves to pass through.
In addition, the Sono system itself will be able to reproduce a variety of pleasant sounds: the singing of whales, the rustling of the forest, the sound of the surf, and the like.
In 2013, this concept project made it to the finals of the James Dyson Award. Unfortunately, it is currently impossible to buy this device, since Sono currently only exists as a prototype.
Active Noise Cancellation System
An effect similar to what we described above (the Sono system) may someday be achieved by an active noise reduction system. Acoustic engineers from Technical University Berlin propose to dampen user-selected street sounds inside the frame using compact loudspeakers mounted between the glass frames.
The operating principle of this system is similar to Sono (“unnecessary” sounds are canceled out by the same sounds emitted in antiphase).
German experts believe that their system can be used not only in residential and administrative premises, but also in cars and airplanes.
The system is currently under development, so more detailed information missing from it.
Overseas inventors also did not stand aside. San Francisco-based Celestial Tribe has offered its Muzo noise-canceling device, which can also provide privacy by creating a so-called “bubble of silence” around interlocutors.
Muzo looks like a small speaker that cuts out unwanted sounds from the user.
The gadget is mounted on a flat surface that serves as a resonator and reproduces sounds that remove extraneous noise. In addition, the device is able to dampen external vibrations, for example, from nearby construction. The device itself can also play pleasant sounds, for example, to improve sleep.
Unlike devices 2 and 3 on our list, Muzo may soon go on sale. Having started on Kickstarter in the summer of 2016, the developers raised more than four hundred thirty thousand dollars (with a planned one hundred thousand). In this regard, pre-orders have already begun on Indiegogo.
According to various sources, this active noise absorber in an apartment or office will reach its first owners in January-February 2017, and its cost will range from 119 to 159 US dollars.