Active noise immunity is a new electronic technology that uses an inverted signal to eliminate noise energy, resisting the original noise and preventing it from entering the human ear through the image of the noise. The article on electronic anti-noise was first published in AES magazine 25 years ago. At that time, researchers used electronic anti-noise technology to eliminate the noise of traditional window air conditioners, and used a lot of circuits, which cost a lot. Although the end is something to gain, the result is at best only a "pet" in the lab. Today, there are digital signal processing chips that are much more powerful and much cheaper, and they can be used to process corresponding anti-noise signals.
Strictly speaking, it is more appropriate to regard active noise immunity as attenuating noise, because anti-noise signals cannot completely eliminate noise. Active anti-noise is a topic worthy of in-depth discussion in the development of electronic products, which has attracted more and more attention from the world. At the beginning, electronic technology workers mainly used wide-bandwidth anti-noise technology such as passive noise dampers to resist noise. Known as passive anti-noise, the passive anti-noise method includes adding sound absorbing material to the sound tube and changing the acoustic impedance of the automobile muffler baffle and the sound tube. However, it is very difficult to make the air conditioner attenuate 10dB noise at low frequencies by passive noise suppression. It requires many very strict measures to make the fan fan the whole system. When the fan load increases, the fan noise The bigger it is. Therefore, passive anti-noise is difficult to achieve the intended purpose. In contrast, active noise immunity is a preferred method of noise immunity. For example, cinemas and factories have air-conditioning equipment. When the frequency is 250Hz, the stable resonance is higher than the ambient noise level by 10dB. Active noise suppression can attenuate the peak signal and significantly improve the noise spectrum. Spread evenly across all frequencies.
in 1989. Digusonr has developed a DSP-based electronic anti-noise processor that is mainly used to reduce the noise of tubes such as air conditioning tubes, pipes, and combustion tubes. Some people have tried to use such processors to solve indoor acoustic problems, such as recording studios. Reverberation transitions between sounds and other acoustic problems.
However, this technique of active noise immunity is difficult to achieve for a number of reasons. First, the processor does not work exactly in real time, and the noise should appear and repeat for at least a fraction of a second to prevent the processor from false triggering. The processor needs a feedback time to amplify the noise signal. If the processor is falsely triggered, it will generate a spurious signal that may be more destructive than current ambient noise. Second, what is even more difficult is the acoustic problem of phase. The cross section of the air conditioning tube is not wide, and the phase of the anti-noise signal is very accurate, which is good for 500Hz or higher. For a wider bandwidth, the air conditioning tube can be divided into multiple cross-sections, but in general it does not make much sense, because the intermediate frequency anti-noise does not have to cost a lot, but it is complicated to carry out electronic anti-noise.
The most difficult to resist noise with a muffler is low frequency noise immunity. Because passive anti-noise will hinder the air-conditioning tube, increase the driving load of the air-conditioning tube, the electronic anti-noise is more true, and can maintain the load efficiency; hybrid anti-noise ------ active anti-noise for low frequency, right The intermediate frequency performs passive noise immunity and is an ideal anti-noise method.
Another achievable anti-noise method is Pewback speaker noise immunity. This speaker does not have a power amplifier, but it can reduce or even eliminate low frequency noise such as air conditioning noise and low frequency reverberation noise. Because the low-frequency reverberation sound below 150Hz has a long decay time and the change is very slow, the Pewback electronic reverberation anti-noise energy plays a certain role. To do this, install the speaker behind the seat and aim at the listener of the particular seat. The distance between the speaker and the ear must be less than 6 inches. This will at least reduce the noise in the frequency range of hundreds of Hertz.
According to the principle of active anti-noise, BOSE and Sennheiser have developed anti-noise headphones. Experts pointed out that the use of active anti-noise technology in headphones is the most realistic.
Place a small microphone (microphone) between the headphone speaker and your tympanic membrane to pick up ambient noise and input it into an electronic circuit that constantly generates noise, and then deliver this ambient noise to the headphone speaker, if everything Normal, not only can reduce the ambient noise by 10dB, but also make the language signal and music signal sound clear without covering the ambient low-frequency noise. Consumer headphones and professional headphones can be used in various environments. .
The first pair of active anti-noise headphones was developed by American BOSE for military pilots. Later, Sennheiser of Germany developed active anti-noise headphones to meet the needs of civil aviation pilots. In large jets, the noise level of the pilot's cockpit is much higher than that of the passenger compartment. The pilot has experienced occupational diseases that often suffer from hearing loss after several years of flight experience. The performance is that the pilot cannot hear clearly in a noisy environment. Broadcast content of the radio station. With active noise suppression, wind noise interference can be reduced by more than 10dB. Therefore, the language communication level in the earphone can be lowered, thereby improving the listening effect.
Today, there are four professional use of active anti-noise headphones. Its manufacturers are Bose, Sennheiser, Telex and NCT. All four headphones use closed earmuffs to block external sounds to reduce noise (other than the lowest frequency noise, other noise can be reduced), using active noise suppression methods to reduce the ambient noise in the lowest frequency range.
Is the earmuffs of the earphones open or closed? It should be said that there is a good time. The earmuffs are open-type earphones, which are comfortable to wear, and the earmuffs are closed-type earphones, which can perform passive anti-noise, especially in the frequency range above the intermediate frequency and the intermediate frequency, and also can perform good low frequency for the continuous sound. Noise reduction. In high noise environments where the acoustic energy exceeds 100 Hz, closed earmuff headphones must be used.
Most professional anti-noise headphones come with a controller that can work for a long time, a battery pack and a rechargeable battery. As far as the headphones themselves are concerned, professional headphones are more sturdy and heavier than consumer headphones. All professional headphones have a fixed microphone or a movable microphone.
Base's anti-noise headphones look big and bulky at first glance, but they are very comfortable to wear. The performance is excellent, although the battery pack is a burden, it must be carried with you, but wearing it for a few hours is not enough, it is highly desirable to use this Headset for inline communication in a noisy environment. This type of earphone has the disadvantage that the total noise attenuation of the earmuffs and active noise suppression seems unnatural, giving the first impression that it is like walking into the anechoic chamber.
The civil aviation anti-noise earphone produced by Telex has good working performance, but it is too heavy and uncomfortable to carry. The circuit also produces a humming sound. Although the sound is very low, the passive attenuation of the earmuff is high. This kind of snoring can still be heard. This headset is suitable for inline communication, and this year Telex has introduced a lighter weight anti-noise headset.
Sennheiser's anti-noise headphones have good noise immunity and performance, and the headphones are also rugged for use in high noise environments.
NCT initially produced Noisebuster consumer headphones, and recently introduced the Proactive2000/3000 series of industrial anti-noise headphones. There are ten models, some with free-moving microphones, some with helmets, and 2000 series headphones. Closed, lightweight, suitable for use in moderately noisy environments, 3000 Series headphones are suitable for use in high noise environments, 2000/3000 series industrial headphones have a very light battery pack and a signal processor for long hours of operation.
Active noise immunity can be used to reduce the noise of continuous sound, such as jets, diesels, fans and other noises that move at constant speed. Because the music signal changes too fast, it can only reduce noise through closed headphones, but can not reduce noise through electronic circuits. The general closed earphones will give people a feeling of ear suffocation, ear canal fever, and wear for a long time. Very uncomfortable. Professional closed earphones, especially earphones for musicians who work exclusively in concert halls, with small sound holes, which can pass signals across the entire audio range and evenly attenuate the signal. Otherwise, An excessively low bass will be unevenly distributed, while intermediate and high frequency signals will gradually block.
If the external noise is very large or deep, all open consumer headphones will be overdriven. For example, headphones made by Koss in Italy are particularly unsuitable for use when the aircraft takes off and land, because the earphone components will shake with the rise and fall. The wearer feels very uncomfortable.
All of the headphones are more or less a sense of oppression, perhaps because the speaker components are not working in their linear range, and the pressure is most pronounced in the high-level ultra-low frequency conditions. But expensive aerospace headsets are less obvious under such conditions, and consumer headphones, after long-term use, give people an unbearable sense of oppression, which is a real problem to be solved. problem.
By the way, the price of headphones is a problem. In just a few years ago, the price of professional active anti-noise headphones was $1,000, and NCT’s consumer headphones were also between $300 and $500, but now there is competition. Sexual branded consumer headphones are well below $200.
The use of active anti-adaptive technology in headphones is only the beginning of this technology. Although the cost of active anti-noise is about five times higher than the cost of conventional mufflers, under certain conditions, this may not be very important. Because the speaker used for active noise immunity does not block engine exhaust, this can save roughly 5% of fuel costs. If an active noise-canceling muffler can be designed, the added cost of active noise immunity is much smaller than that of a conventional muffler, not to mention the energy saved during vehicle operation. Active noise immunity is a new electronic technology that uses an inverted signal to eliminate noise energy, resisting the original noise and preventing it from entering the human ear through the image of the noise. The article on electronic anti-noise was first published in AES magazine 25 years ago. At that time, researchers used electronic anti-noise technology to eliminate the noise of traditional window air conditioners, and used a lot of circuits, which cost a lot. Although the end is something to gain, the result is at best only a "pet" in the lab. Today, there are digital signal processing chips that are much more powerful and much cheaper, and they can be used to process corresponding anti-noise signals.
Strictly speaking, it is more appropriate to regard active noise immunity as attenuating noise, because anti-noise signals cannot completely eliminate noise. Active anti-noise is a topic worthy of in-depth discussion in the development of electronic products, which has attracted more and more attention from the world. At the beginning, electronic technology workers mainly used wide-bandwidth anti-noise technology such as passive noise dampers to resist noise. Known as passive anti-noise, the passive anti-noise method includes adding sound absorbing material to the sound tube and changing the acoustic impedance of the automobile muffler baffle and the sound tube. However, it is very difficult to make the air conditioner attenuate 10dB noise at low frequencies by passive noise suppression. It requires many very strict measures to make the fan fan the whole system. When the fan load increases, the fan noise The bigger it is. Therefore, passive anti-noise is difficult to achieve the intended purpose. In contrast, active noise immunity is a preferred method of noise immunity. For example, cinemas and factories have air-conditioning equipment. When the frequency is 250Hz, the stable resonance is higher than the ambient noise level by 10dB. Active noise suppression can attenuate the peak signal and significantly improve the noise spectrum. Spread evenly across all frequencies.
in 1989. Digusonr has developed a DSP-based electronic anti-noise processor that is mainly used to reduce the noise of tubes such as air conditioning tubes, pipes, and combustion tubes. Some people have tried to use such processors to solve indoor acoustic problems, such as recording studios. Reverberation transitions between sounds and other acoustic problems.
However, this technique of active noise immunity is difficult to achieve for a number of reasons. First, the processor does not work exactly in real time, and the noise should appear and repeat for at least a fraction of a second to prevent the processor from false triggering. The processor needs a feedback time to amplify the noise signal. If the processor is falsely triggered, it will generate a spurious signal that may be more destructive than current ambient noise. Second, what is even more difficult is the acoustic problem of phase. The cross section of the air conditioning tube is not wide, and the phase of the anti-noise signal is very accurate, which is good for 500Hz or higher. For a wider bandwidth, the air conditioning tube can be divided into multiple cross-sections, but in general it does not make much sense, because the intermediate frequency anti-noise does not have to cost a lot, but it is complicated to carry out electronic anti-noise.
The most difficult to resist noise with a muffler is low frequency noise immunity. Because passive anti-noise will hinder the air-conditioning tube, increase the driving load of the air-conditioning tube, the electronic anti-noise is more true, and can maintain the load efficiency; hybrid anti-noise ------ active anti-noise for low frequency, right The intermediate frequency performs passive noise immunity and is an ideal anti-noise method.
Another achievable anti-noise method is Pewback speaker noise immunity. This speaker does not have a power amplifier, but it can reduce or even eliminate low frequency noise such as air conditioning noise and low frequency reverberation noise. Because the low-frequency reverberation sound below 150Hz has a long decay time and the change is very slow, the Pewback electronic reverberation anti-noise energy plays a certain role. To do this, install the speaker behind the seat and aim at the listener of the particular seat. The distance between the speaker and the ear must be less than 6 inches. This will at least reduce the noise in the frequency range of hundreds of Hertz.
According to the principle of active anti-noise, BOSE and Sennheiser have developed anti-noise headphones. Experts pointed out that the use of active anti-noise technology in headphones is the most realistic.
Place a small microphone (microphone) between the headphone speaker and your tympanic membrane to pick up ambient noise and input it into an electronic circuit that constantly generates noise, and then deliver this ambient noise to the headphone speaker, if everything Normal, not only can reduce the ambient noise by 10dB, but also make the language signal and music signal sound clear without covering the ambient low-frequency noise. Consumer headphones and professional headphones can be used in various environments. .
The first pair of active anti-noise headphones was developed by American BOSE for military pilots. Later, Sennheiser of Germany developed active anti-noise headphones to meet the needs of civil aviation pilots. In large jets, the noise level of the pilot's cockpit is much higher than that of the passenger compartment. The pilot has experienced occupational diseases that often suffer from hearing loss after several years of flight experience. The performance is that the pilot cannot hear clearly in a noisy environment. Broadcast content of the radio station. With active noise suppression, wind noise interference can be reduced by more than 10dB. Therefore, the language communication level in the earphone can be lowered, thereby improving the listening effect.
Today, there are four professional use of active anti-noise headphones. Its manufacturers are Bose, Sennheiser, Telex and NCT. All four headphones use closed earmuffs to block external sounds to reduce noise (other than the lowest frequency noise, other noise can be reduced), using active noise suppression methods to reduce the ambient noise in the lowest frequency range.
Is the earmuffs of the earphones open or closed? It should be said that there is a good time. The earmuffs are open-type earphones, which are comfortable to wear, and the earmuffs are closed-type earphones, which can perform passive anti-noise, especially in the frequency range above the intermediate frequency and the intermediate frequency, and also can perform good low frequency for the continuous sound. Noise reduction. In high noise environments where the acoustic energy exceeds 100 Hz, closed earmuff headphones must be used.
Most professional anti-noise headphones come with a controller that can work for a long time, a battery pack and a rechargeable battery. As far as the headphones themselves are concerned, professional headphones are more sturdy and heavier than consumer headphones. All professional headphones have a fixed microphone or a movable microphone.
Base's anti-noise headphones look big and bulky at first glance, but they are very comfortable to wear. The performance is excellent, although the battery pack is a burden, it must be carried with you, but wearing it for a few hours is not enough, it is highly desirable to use this headset for inline communication in a noisy environment. This type of earphone has the disadvantage that the total noise attenuation of the earmuffs and active noise suppression seems unnatural, giving the first impression that it is like walking into the anechoic chamber.
The civil aviation anti-noise earphone produced by Telex has good working performance, but it is too heavy and uncomfortable to carry. The circuit also produces a humming sound. Although the sound is very low, the passive attenuation of the earmuff is high. This kind of snoring can still be heard. This headset is suitable for inline communication, and this year Telex has introduced a lighter weight anti-noise headset.
Sennheiser's anti-noise headphones have good noise immunity and performance, and the headphones are also rugged for use in high noise environments.
NCT initially produced Noisebuster consumer headphones, and recently introduced the Proactive2000/3000 series of industrial anti-noise headphones. There are ten models, some with free-moving microphones, some with helmets, and 2000 series headphones. Closed, lightweight, suitable for use in moderately noisy environments, 3000 Series headphones are suitable for use in high noise environments, 2000/3000 series industrial headphones have a very light battery pack and a signal processor for long hours of operation.
Active noise immunity can be used to reduce the noise of continuous sound, such as jets, diesels, fans and other noises that move at constant speed. Because the music signal changes too fast, it can only reduce noise through closed headphones, but can not reduce noise through electronic circuits. The general closed earphones will give people a feeling of ear suffocation, ear canal fever, and wear for a long time. Very uncomfortable. Professional closed earphones, especially earphones for musicians who work exclusively in concert halls, with small sound holes, which can pass signals across the entire audio range and evenly attenuate the signal. Otherwise, An excessively low bass will be unevenly distributed, while intermediate and high frequency signals will gradually block.
If the external noise is very large or deep, all open consumer headphones will be overdriven. For example, headphones made by Koss in Italy are particularly unsuitable for use when the aircraft takes off and land, because the earphone components will shake with the rise and fall. The wearer feels very uncomfortable.
All of the headphones are more or less a sense of oppression, perhaps because the speaker components are not working in their linear range, and the pressure is most pronounced in the high-level ultra-low frequency conditions. But expensive aerospace headsets are less obvious under such conditions, and consumer headphones, after long-term use, give people an unbearable sense of oppression, which is a real problem to be solved. problem.
By the way, the price of headphones is a problem. In just a few years ago, the price of professional active anti-noise headphones was $1,000, and NCT’s consumer headphones were also between $300 and $500, but now there is competition. Sexual branded consumer headphones are well below $200.
The use of active anti-adaptive technology in headphones is only the beginning of this technology. Although the cost of active anti-noise is about five times higher than the cost of conventional mufflers, under certain conditions, this may not be very important. Because the speaker used for active noise immunity does not block engine exhaust, this can save roughly 5% of fuel costs. If an active noise-canceling muffler can be designed, the added cost of active noise immunity is much smaller than that of a conventional muffler, not to mention the energy saved during vehicle operation. Active noise immunity is a new electronic technology that uses an inverted signal to eliminate noise energy, resisting the original noise and preventing it from entering the human ear through the image of the noise. The article on electronic anti-noise was first published in AES magazine 25 years ago. At that time, researchers used electronic anti-noise technology to eliminate the noise of traditional window air conditioners, and used a lot of circuits, which cost a lot. Although the end is something to gain, the result is at best only a "pet" in the lab. Today, there are digital signal processing chips that are much more powerful and much cheaper, and they can be used to process corresponding anti-noise signals.
Strictly speaking, it is more appropriate to regard active noise immunity as attenuating noise, because anti-noise signals cannot completely eliminate noise. Active anti-noise is a topic worthy of in-depth discussion in the development of electronic products, which has attracted more and more attention from the world. At the beginning, electronic technology workers mainly used wide-bandwidth anti-noise technology such as passive noise dampers to resist noise. Known as passive anti-noise, the passive anti-noise method includes adding sound absorbing material to the sound tube and changing the acoustic impedance of the automobile muffler baffle and the sound tube. However, it is very difficult to make the air conditioner attenuate 10dB noise at low frequencies by passive noise suppression. It requires many very strict measures to make the fan fan the whole system. When the fan load increases, the fan noise The bigger it is. Therefore, passive anti-noise is difficult to achieve the intended purpose. In contrast, active noise immunity is a preferred method of noise immunity. For example, cinemas and factories have air-conditioning equipment. When the frequency is 250Hz, the stable resonance is higher than the ambient noise level by 10dB. Active noise suppression can attenuate the peak signal and significantly improve the noise spectrum. Spread evenly across all frequencies.
in 1989. Digusonr has developed a DSP-based electronic anti-noise processor that is mainly used to reduce the noise of tubes such as air conditioning tubes, pipes, and combustion tubes. Some people have tried to use such processors to solve indoor acoustic problems, such as recording studios. Reverberation transitions between sounds and other acoustic problems.
However, this technique of active noise immunity is difficult to achieve for a number of reasons. First, the processor does not work exactly in real time, and the noise should appear and repeat for at least a fraction of a second to prevent the processor from false triggering. The processor needs a feedback time to amplify the noise signal. If the processor is falsely triggered, it will generate a spurious signal that may be more destructive than current ambient noise. Second, what is even more difficult is the acoustic problem of phase. The cross section of the air conditioning tube is not wide, and the phase of the anti-noise signal is very accurate, which is good for 500Hz or higher. For a wider bandwidth, the air conditioning tube can be divided into multiple cross-sections, but in general it does not make much sense, because the intermediate frequency anti-noise does not have to cost a lot, but it is complicated to carry out electronic anti-noise.
The most difficult to resist noise with a muffler is low frequency noise immunity. Because passive anti-noise will hinder the air-conditioning tube, increase the driving load of the air-conditioning tube, the electronic anti-noise is more true, and can maintain the load efficiency; hybrid anti-noise ------ active anti-noise for low frequency, right The intermediate frequency performs passive noise immunity and is an ideal anti-noise method.
Another achievable anti-noise method is Pewback speaker noise immunity. This speaker does not have a power amplifier, but it can reduce or even eliminate low frequency noise such as air conditioning noise and low frequency reverberation noise. Because the low-frequency reverberation sound below 150Hz has a long decay time and the change is very slow, the Pewback electronic reverberation anti-noise energy plays a certain role. To do this, install the speaker behind the seat and aim at the listener of the particular seat. The distance between the speaker and the ear must be less than 6 inches. This will at least reduce the noise in the frequency range of hundreds of Hertz.
According to the principle of active anti-noise, BOSE and Sennheiser have developed anti-noise headphones. Experts pointed out that the use of active anti-noise technology in headphones is the most realistic.
Place a small microphone (microphone) between the headphone speaker and your tympanic membrane to pick up ambient noise and input it into an electronic circuit that constantly generates noise, and then deliver this ambient noise to the headphone speaker, if everything Normal, not only can reduce the ambient noise by 10dB, but also make the language signal and music signal sound clear without covering the ambient low-frequency noise. Consumer headphones and professional headphones can be used in various environments. .
The first pair of active anti-noise headphones was developed by American BOSE for military pilots. Later, Sennheiser of Germany developed active anti-noise headphones to meet the needs of civil aviation pilots. In large jets, the noise level of the pilot's cockpit is much higher than that of the passenger compartment. The pilot has experienced occupational diseases that often suffer from hearing loss after several years of flight experience. The performance is that the pilot cannot hear clearly in a noisy environment. Broadcast content of the radio station. With active noise suppression, wind noise interference can be reduced by more than 10dB. Therefore, the language communication level in the earphone can be lowered, thereby improving the listening effect.
Today, there are four professional use of active anti-noise headphones. Its manufacturers are Bose, Sennheiser, Telex and NCT. All four headphones use closed earmuffs to block external sounds to reduce noise (other than the lowest frequency noise, other noise can be reduced), using active noise suppression methods to reduce the ambient noise in the lowest frequency range.
Is the earmuffs of the earphones open or closed? It should be said that there is a good time. The earmuffs are open-type earphones, which are comfortable to wear, and the earmuffs are closed-type earphones, which can perform passive anti-noise, especially in the frequency range above the intermediate frequency and the intermediate frequency, and also can perform good low frequency for the continuous sound. Noise reduction. In high noise environments where the acoustic energy exceeds 100 Hz, closed earmuff headphones must be used.
Most professional anti-noise headphones come with a controller that can work for a long time, a battery pack and a rechargeable battery. As far as the headphones themselves are concerned, professional headphones are more sturdy and heavier than consumer headphones. All professional headphones have a fixed microphone or a movable microphone.
Base's anti-noise headphones look big and bulky at first glance, but they are very comfortable to wear. The performance is excellent, although the battery pack is a burden, it must be carried with you, but wearing it for a few hours is not enough, it is highly desirable to use this headset for inline communication in a noisy environment. This type of earphone has the disadvantage that the total noise attenuation of the earmuffs and active noise suppression seems unnatural, giving the first impression that it is like walking into the anechoic chamber.
The civil aviation anti-noise earphone produced by Telex has good working performance, but it is too heavy and uncomfortable to carry. The circuit also produces a humming sound. Although the sound is very low, the passive attenuation of the earmuff is high. This kind of snoring can still be heard. This headset is suitable for inline communication, and this year Telex has introduced a lighter weight anti-noise headset.
Sennheiser's anti-noise headphones have good noise immunity and performance, and the headphones are also rugged for use in high noise environments.
NCT initially produced Noisebuster consumer headphones, and recently introduced the Proactive2000/3000 series of industrial anti-noise headphones. There are ten models, some with free-moving microphones, some with helmets, and 2000 series headphones. Closed, lightweight, suitable for use in moderately noisy environments, 3000 Series headphones are suitable for use in high noise environments, 2000/3000 series industrial headphones have a very light battery pack and a signal processor for long hours of operation.
Active noise immunity can be used to reduce the noise of continuous sound, such as jets, diesels, fans and other noises that move at constant speed. Because the music signal changes too fast, it can only reduce noise through closed headphones, but can not reduce noise through electronic circuits. The general closed earphones will give people a feeling of ear suffocation, ear canal fever, and wear for a long time. Very uncomfortable. Professional closed earphones, especially earphones for musicians who work exclusively in concert halls, with small sound holes, which can pass signals across the entire audio range and evenly attenuate the signal. Otherwise, An excessively low bass will be unevenly distributed, while intermediate and high frequency signals will gradually block.
If the external noise is very large or deep, all open consumer headphones will be overdriven. For example, headphones made by Koss in Italy are particularly unsuitable for use when the aircraft takes off and land, because the earphone components will shake with the rise and fall. The wearer feels very uncomfortable.
All of the headphones are more or less a sense of oppression, perhaps because the speaker components are not working in their linear range, and the pressure is most pronounced in the high-level ultra-low frequency conditions. But expensive aerospace headsets are less obvious under such conditions, and consumer headphones, after long-term use, give people an unbearable sense of oppression, which is a real problem to be solved. problem.
By the way, the price of headphones is a problem. In just a few years ago, the price of professional active anti-noise headphones was $1,000, and NCT’s consumer headphones were also between $300 and $500, but now there is competition. Sexual branded consumer headphones are well below $200.
The use of active anti-adaptive technology in headphones is only the beginning of this technology. Although the cost of active anti-noise is about five times higher than the cost of conventional mufflers, under certain conditions, this may not be very important. Because the speaker used for active noise immunity does not block engine exhaust, this can save roughly 5% of fuel costs. If an active noise-canceling muffler can be designed, the added cost of active noise immunity is much smaller than that of a conventional muffler, not to mention the energy saved during vehicle operation.
Strictly speaking, it is more appropriate to regard active noise immunity as attenuating noise, because anti-noise signals cannot completely eliminate noise. Active anti-noise is a topic worthy of in-depth discussion in the development of electronic products, which has attracted more and more attention from the world. At the beginning, electronic technology workers mainly used wide-bandwidth anti-noise technology such as passive noise dampers to resist noise. Known as passive anti-noise, the passive anti-noise method includes adding sound absorbing material to the sound tube and changing the acoustic impedance of the automobile muffler baffle and the sound tube. However, it is very difficult to make the air conditioner attenuate 10dB noise at low frequencies by passive noise suppression. It requires many very strict measures to make the fan fan the whole system. When the fan load increases, the fan noise The bigger it is. Therefore, passive anti-noise is difficult to achieve the intended purpose. In contrast, active noise immunity is a preferred method of noise immunity. For example, cinemas and factories have air-conditioning equipment. When the frequency is 250Hz, the stable resonance is higher than the ambient noise level by 10dB. Active noise suppression can attenuate the peak signal and significantly improve the noise spectrum. Spread evenly across all frequencies.
in 1989. Digusonr has developed a DSP-based electronic anti-noise processor that is mainly used to reduce the noise of tubes such as air conditioning tubes, pipes, and combustion tubes. Some people have tried to use such processors to solve indoor acoustic problems, such as recording studios. Reverberation transitions between sounds and other acoustic problems.
However, this technique of active noise immunity is difficult to achieve for a number of reasons. First, the processor does not work exactly in real time, and the noise should appear and repeat for at least a fraction of a second to prevent the processor from false triggering. The processor needs a feedback time to amplify the noise signal. If the processor is falsely triggered, it will generate a spurious signal that may be more destructive than current ambient noise. Second, what is even more difficult is the acoustic problem of phase. The cross section of the air conditioning tube is not wide, and the phase of the anti-noise signal is very accurate, which is good for 500Hz or higher. For a wider bandwidth, the air conditioning tube can be divided into multiple cross-sections, but in general it does not make much sense, because the intermediate frequency anti-noise does not have to cost a lot, but it is complicated to carry out electronic anti-noise.
The most difficult to resist noise with a muffler is low frequency noise immunity. Because passive anti-noise will hinder the air-conditioning tube, increase the driving load of the air-conditioning tube, the electronic anti-noise is more true, and can maintain the load efficiency; hybrid anti-noise ------ active anti-noise for low frequency, right The intermediate frequency performs passive noise immunity and is an ideal anti-noise method.
Another achievable anti-noise method is Pewback speaker noise immunity. This speaker does not have a power amplifier, but it can reduce or even eliminate low frequency noise such as air conditioning noise and low frequency reverberation noise. Because the low-frequency reverberation sound below 150Hz has a long decay time and the change is very slow, the Pewback electronic reverberation anti-noise energy plays a certain role. To do this, install the speaker behind the seat and aim at the listener of the particular seat. The distance between the speaker and the ear must be less than 6 inches. This will at least reduce the noise in the frequency range of hundreds of Hertz.
According to the principle of active anti-noise, BOSE and Sennheiser have developed anti-noise headphones. Experts pointed out that the use of active anti-noise technology in headphones is the most realistic.
Place a small microphone (microphone) between the headphone speaker and your tympanic membrane to pick up ambient noise and input it into an electronic circuit that constantly generates noise, and then deliver this ambient noise to the headphone speaker, if everything Normal, not only can reduce the ambient noise by 10dB, but also make the language signal and music signal sound clear without covering the ambient low-frequency noise. Consumer headphones and professional headphones can be used in various environments. .
The first pair of active anti-noise headphones was developed by American BOSE for military pilots. Later, Sennheiser of Germany developed active anti-noise headphones to meet the needs of civil aviation pilots. In large jets, the noise level of the pilot's cockpit is much higher than that of the passenger compartment. The pilot has experienced occupational diseases that often suffer from hearing loss after several years of flight experience. The performance is that the pilot cannot hear clearly in a noisy environment. Broadcast content of the radio station. With active noise suppression, wind noise interference can be reduced by more than 10dB. Therefore, the language communication level in the earphone can be lowered, thereby improving the listening effect.
Today, there are four professional use of active anti-noise headphones. Its manufacturers are Bose, Sennheiser, Telex and NCT. All four headphones use closed earmuffs to block external sounds to reduce noise (other than the lowest frequency noise, other noise can be reduced), using active noise suppression methods to reduce the ambient noise in the lowest frequency range.
Is the earmuffs of the earphones open or closed? It should be said that there is a good time. The earmuffs are open-type earphones, which are comfortable to wear, and the earmuffs are closed-type earphones, which can perform passive anti-noise, especially in the frequency range above the intermediate frequency and the intermediate frequency, and also can perform good low frequency for the continuous sound. Noise reduction. In high noise environments where the acoustic energy exceeds 100 Hz, closed earmuff headphones must be used.
Most professional anti-noise headphones come with a controller that can work for a long time, a battery pack and a rechargeable battery. As far as the headphones themselves are concerned, professional headphones are more sturdy and heavier than consumer headphones. All professional headphones have a fixed microphone or a movable microphone.
Base's anti-noise headphones look big and bulky at first glance, but they are very comfortable to wear. The performance is excellent, although the battery pack is a burden, it must be carried with you, but wearing it for a few hours is not enough, it is highly desirable to use this Headset for inline communication in a noisy environment. This type of earphone has the disadvantage that the total noise attenuation of the earmuffs and active noise suppression seems unnatural, giving the first impression that it is like walking into the anechoic chamber.
The civil aviation anti-noise earphone produced by Telex has good working performance, but it is too heavy and uncomfortable to carry. The circuit also produces a humming sound. Although the sound is very low, the passive attenuation of the earmuff is high. This kind of snoring can still be heard. This headset is suitable for inline communication, and this year Telex has introduced a lighter weight anti-noise headset.
Sennheiser's anti-noise headphones have good noise immunity and performance, and the headphones are also rugged for use in high noise environments.
NCT initially produced Noisebuster consumer headphones, and recently introduced the Proactive2000/3000 series of industrial anti-noise headphones. There are ten models, some with free-moving microphones, some with helmets, and 2000 series headphones. Closed, lightweight, suitable for use in moderately noisy environments, 3000 Series headphones are suitable for use in high noise environments, 2000/3000 series industrial headphones have a very light battery pack and a signal processor for long hours of operation.
Active noise immunity can be used to reduce the noise of continuous sound, such as jets, diesels, fans and other noises that move at constant speed. Because the music signal changes too fast, it can only reduce noise through closed headphones, but can not reduce noise through electronic circuits. The general closed earphones will give people a feeling of ear suffocation, ear canal fever, and wear for a long time. Very uncomfortable. Professional closed earphones, especially earphones for musicians who work exclusively in concert halls, with small sound holes, which can pass signals across the entire audio range and evenly attenuate the signal. Otherwise, An excessively low bass will be unevenly distributed, while intermediate and high frequency signals will gradually block.
If the external noise is very large or deep, all open consumer headphones will be overdriven. For example, headphones made by Koss in Italy are particularly unsuitable for use when the aircraft takes off and land, because the earphone components will shake with the rise and fall. The wearer feels very uncomfortable.
All of the headphones are more or less a sense of oppression, perhaps because the speaker components are not working in their linear range, and the pressure is most pronounced in the high-level ultra-low frequency conditions. But expensive aerospace headsets are less obvious under such conditions, and consumer headphones, after long-term use, give people an unbearable sense of oppression, which is a real problem to be solved. problem.
By the way, the price of headphones is a problem. In just a few years ago, the price of professional active anti-noise headphones was $1,000, and NCT’s consumer headphones were also between $300 and $500, but now there is competition. Sexual branded consumer headphones are well below $200.
The use of active anti-adaptive technology in headphones is only the beginning of this technology. Although the cost of active anti-noise is about five times higher than the cost of conventional mufflers, under certain conditions, this may not be very important. Because the speaker used for active noise immunity does not block engine exhaust, this can save roughly 5% of fuel costs. If an active noise-canceling muffler can be designed, the added cost of active noise immunity is much smaller than that of a conventional muffler, not to mention the energy saved during vehicle operation. Active noise immunity is a new electronic technology that uses an inverted signal to eliminate noise energy, resisting the original noise and preventing it from entering the human ear through the image of the noise. The article on electronic anti-noise was first published in AES magazine 25 years ago. At that time, researchers used electronic anti-noise technology to eliminate the noise of traditional window air conditioners, and used a lot of circuits, which cost a lot. Although the end is something to gain, the result is at best only a "pet" in the lab. Today, there are digital signal processing chips that are much more powerful and much cheaper, and they can be used to process corresponding anti-noise signals.
Strictly speaking, it is more appropriate to regard active noise immunity as attenuating noise, because anti-noise signals cannot completely eliminate noise. Active anti-noise is a topic worthy of in-depth discussion in the development of electronic products, which has attracted more and more attention from the world. At the beginning, electronic technology workers mainly used wide-bandwidth anti-noise technology such as passive noise dampers to resist noise. Known as passive anti-noise, the passive anti-noise method includes adding sound absorbing material to the sound tube and changing the acoustic impedance of the automobile muffler baffle and the sound tube. However, it is very difficult to make the air conditioner attenuate 10dB noise at low frequencies by passive noise suppression. It requires many very strict measures to make the fan fan the whole system. When the fan load increases, the fan noise The bigger it is. Therefore, passive anti-noise is difficult to achieve the intended purpose. In contrast, active noise immunity is a preferred method of noise immunity. For example, cinemas and factories have air-conditioning equipment. When the frequency is 250Hz, the stable resonance is higher than the ambient noise level by 10dB. Active noise suppression can attenuate the peak signal and significantly improve the noise spectrum. Spread evenly across all frequencies.
in 1989. Digusonr has developed a DSP-based electronic anti-noise processor that is mainly used to reduce the noise of tubes such as air conditioning tubes, pipes, and combustion tubes. Some people have tried to use such processors to solve indoor acoustic problems, such as recording studios. Reverberation transitions between sounds and other acoustic problems.
However, this technique of active noise immunity is difficult to achieve for a number of reasons. First, the processor does not work exactly in real time, and the noise should appear and repeat for at least a fraction of a second to prevent the processor from false triggering. The processor needs a feedback time to amplify the noise signal. If the processor is falsely triggered, it will generate a spurious signal that may be more destructive than current ambient noise. Second, what is even more difficult is the acoustic problem of phase. The cross section of the air conditioning tube is not wide, and the phase of the anti-noise signal is very accurate, which is good for 500Hz or higher. For a wider bandwidth, the air conditioning tube can be divided into multiple cross-sections, but in general it does not make much sense, because the intermediate frequency anti-noise does not have to cost a lot, but it is complicated to carry out electronic anti-noise.
The most difficult to resist noise with a muffler is low frequency noise immunity. Because passive anti-noise will hinder the air-conditioning tube, increase the driving load of the air-conditioning tube, the electronic anti-noise is more true, and can maintain the load efficiency; hybrid anti-noise ------ active anti-noise for low frequency, right The intermediate frequency performs passive noise immunity and is an ideal anti-noise method.
Another achievable anti-noise method is Pewback speaker noise immunity. This speaker does not have a power amplifier, but it can reduce or even eliminate low frequency noise such as air conditioning noise and low frequency reverberation noise. Because the low-frequency reverberation sound below 150Hz has a long decay time and the change is very slow, the Pewback electronic reverberation anti-noise energy plays a certain role. To do this, install the speaker behind the seat and aim at the listener of the particular seat. The distance between the speaker and the ear must be less than 6 inches. This will at least reduce the noise in the frequency range of hundreds of Hertz.
According to the principle of active anti-noise, BOSE and Sennheiser have developed anti-noise headphones. Experts pointed out that the use of active anti-noise technology in headphones is the most realistic.
Place a small microphone (microphone) between the headphone speaker and your tympanic membrane to pick up ambient noise and input it into an electronic circuit that constantly generates noise, and then deliver this ambient noise to the headphone speaker, if everything Normal, not only can reduce the ambient noise by 10dB, but also make the language signal and music signal sound clear without covering the ambient low-frequency noise. Consumer headphones and professional headphones can be used in various environments. .
The first pair of active anti-noise headphones was developed by American BOSE for military pilots. Later, Sennheiser of Germany developed active anti-noise headphones to meet the needs of civil aviation pilots. In large jets, the noise level of the pilot's cockpit is much higher than that of the passenger compartment. The pilot has experienced occupational diseases that often suffer from hearing loss after several years of flight experience. The performance is that the pilot cannot hear clearly in a noisy environment. Broadcast content of the radio station. With active noise suppression, wind noise interference can be reduced by more than 10dB. Therefore, the language communication level in the earphone can be lowered, thereby improving the listening effect.
Today, there are four professional use of active anti-noise headphones. Its manufacturers are Bose, Sennheiser, Telex and NCT. All four headphones use closed earmuffs to block external sounds to reduce noise (other than the lowest frequency noise, other noise can be reduced), using active noise suppression methods to reduce the ambient noise in the lowest frequency range.
Is the earmuffs of the earphones open or closed? It should be said that there is a good time. The earmuffs are open-type earphones, which are comfortable to wear, and the earmuffs are closed-type earphones, which can perform passive anti-noise, especially in the frequency range above the intermediate frequency and the intermediate frequency, and also can perform good low frequency for the continuous sound. Noise reduction. In high noise environments where the acoustic energy exceeds 100 Hz, closed earmuff headphones must be used.
Most professional anti-noise headphones come with a controller that can work for a long time, a battery pack and a rechargeable battery. As far as the headphones themselves are concerned, professional headphones are more sturdy and heavier than consumer headphones. All professional headphones have a fixed microphone or a movable microphone.
Base's anti-noise headphones look big and bulky at first glance, but they are very comfortable to wear. The performance is excellent, although the battery pack is a burden, it must be carried with you, but wearing it for a few hours is not enough, it is highly desirable to use this headset for inline communication in a noisy environment. This type of earphone has the disadvantage that the total noise attenuation of the earmuffs and active noise suppression seems unnatural, giving the first impression that it is like walking into the anechoic chamber.
The civil aviation anti-noise earphone produced by Telex has good working performance, but it is too heavy and uncomfortable to carry. The circuit also produces a humming sound. Although the sound is very low, the passive attenuation of the earmuff is high. This kind of snoring can still be heard. This headset is suitable for inline communication, and this year Telex has introduced a lighter weight anti-noise headset.
Sennheiser's anti-noise headphones have good noise immunity and performance, and the headphones are also rugged for use in high noise environments.
NCT initially produced Noisebuster consumer headphones, and recently introduced the Proactive2000/3000 series of industrial anti-noise headphones. There are ten models, some with free-moving microphones, some with helmets, and 2000 series headphones. Closed, lightweight, suitable for use in moderately noisy environments, 3000 Series headphones are suitable for use in high noise environments, 2000/3000 series industrial headphones have a very light battery pack and a signal processor for long hours of operation.
Active noise immunity can be used to reduce the noise of continuous sound, such as jets, diesels, fans and other noises that move at constant speed. Because the music signal changes too fast, it can only reduce noise through closed headphones, but can not reduce noise through electronic circuits. The general closed earphones will give people a feeling of ear suffocation, ear canal fever, and wear for a long time. Very uncomfortable. Professional closed earphones, especially earphones for musicians who work exclusively in concert halls, with small sound holes, which can pass signals across the entire audio range and evenly attenuate the signal. Otherwise, An excessively low bass will be unevenly distributed, while intermediate and high frequency signals will gradually block.
If the external noise is very large or deep, all open consumer headphones will be overdriven. For example, headphones made by Koss in Italy are particularly unsuitable for use when the aircraft takes off and land, because the earphone components will shake with the rise and fall. The wearer feels very uncomfortable.
All of the headphones are more or less a sense of oppression, perhaps because the speaker components are not working in their linear range, and the pressure is most pronounced in the high-level ultra-low frequency conditions. But expensive aerospace headsets are less obvious under such conditions, and consumer headphones, after long-term use, give people an unbearable sense of oppression, which is a real problem to be solved. problem.
By the way, the price of headphones is a problem. In just a few years ago, the price of professional active anti-noise headphones was $1,000, and NCT’s consumer headphones were also between $300 and $500, but now there is competition. Sexual branded consumer headphones are well below $200.
The use of active anti-adaptive technology in headphones is only the beginning of this technology. Although the cost of active anti-noise is about five times higher than the cost of conventional mufflers, under certain conditions, this may not be very important. Because the speaker used for active noise immunity does not block engine exhaust, this can save roughly 5% of fuel costs. If an active noise-canceling muffler can be designed, the added cost of active noise immunity is much smaller than that of a conventional muffler, not to mention the energy saved during vehicle operation. Active noise immunity is a new electronic technology that uses an inverted signal to eliminate noise energy, resisting the original noise and preventing it from entering the human ear through the image of the noise. The article on electronic anti-noise was first published in AES magazine 25 years ago. At that time, researchers used electronic anti-noise technology to eliminate the noise of traditional window air conditioners, and used a lot of circuits, which cost a lot. Although the end is something to gain, the result is at best only a "pet" in the lab. Today, there are digital signal processing chips that are much more powerful and much cheaper, and they can be used to process corresponding anti-noise signals.
Strictly speaking, it is more appropriate to regard active noise immunity as attenuating noise, because anti-noise signals cannot completely eliminate noise. Active anti-noise is a topic worthy of in-depth discussion in the development of electronic products, which has attracted more and more attention from the world. At the beginning, electronic technology workers mainly used wide-bandwidth anti-noise technology such as passive noise dampers to resist noise. Known as passive anti-noise, the passive anti-noise method includes adding sound absorbing material to the sound tube and changing the acoustic impedance of the automobile muffler baffle and the sound tube. However, it is very difficult to make the air conditioner attenuate 10dB noise at low frequencies by passive noise suppression. It requires many very strict measures to make the fan fan the whole system. When the fan load increases, the fan noise The bigger it is. Therefore, passive anti-noise is difficult to achieve the intended purpose. In contrast, active noise immunity is a preferred method of noise immunity. For example, cinemas and factories have air-conditioning equipment. When the frequency is 250Hz, the stable resonance is higher than the ambient noise level by 10dB. Active noise suppression can attenuate the peak signal and significantly improve the noise spectrum. Spread evenly across all frequencies.
in 1989. Digusonr has developed a DSP-based electronic anti-noise processor that is mainly used to reduce the noise of tubes such as air conditioning tubes, pipes, and combustion tubes. Some people have tried to use such processors to solve indoor acoustic problems, such as recording studios. Reverberation transitions between sounds and other acoustic problems.
However, this technique of active noise immunity is difficult to achieve for a number of reasons. First, the processor does not work exactly in real time, and the noise should appear and repeat for at least a fraction of a second to prevent the processor from false triggering. The processor needs a feedback time to amplify the noise signal. If the processor is falsely triggered, it will generate a spurious signal that may be more destructive than current ambient noise. Second, what is even more difficult is the acoustic problem of phase. The cross section of the air conditioning tube is not wide, and the phase of the anti-noise signal is very accurate, which is good for 500Hz or higher. For a wider bandwidth, the air conditioning tube can be divided into multiple cross-sections, but in general it does not make much sense, because the intermediate frequency anti-noise does not have to cost a lot, but it is complicated to carry out electronic anti-noise.
The most difficult to resist noise with a muffler is low frequency noise immunity. Because passive anti-noise will hinder the air-conditioning tube, increase the driving load of the air-conditioning tube, the electronic anti-noise is more true, and can maintain the load efficiency; hybrid anti-noise ------ active anti-noise for low frequency, right The intermediate frequency performs passive noise immunity and is an ideal anti-noise method.
Another achievable anti-noise method is Pewback speaker noise immunity. This speaker does not have a power amplifier, but it can reduce or even eliminate low frequency noise such as air conditioning noise and low frequency reverberation noise. Because the low-frequency reverberation sound below 150Hz has a long decay time and the change is very slow, the Pewback electronic reverberation anti-noise energy plays a certain role. To do this, install the speaker behind the seat and aim at the listener of the particular seat. The distance between the speaker and the ear must be less than 6 inches. This will at least reduce the noise in the frequency range of hundreds of Hertz.
According to the principle of active anti-noise, BOSE and Sennheiser have developed anti-noise headphones. Experts pointed out that the use of active anti-noise technology in headphones is the most realistic.
Place a small microphone (microphone) between the headphone speaker and your tympanic membrane to pick up ambient noise and input it into an electronic circuit that constantly generates noise, and then deliver this ambient noise to the headphone speaker, if everything Normal, not only can reduce the ambient noise by 10dB, but also make the language signal and music signal sound clear without covering the ambient low-frequency noise. Consumer headphones and professional headphones can be used in various environments. .
The first pair of active anti-noise headphones was developed by American BOSE for military pilots. Later, Sennheiser of Germany developed active anti-noise headphones to meet the needs of civil aviation pilots. In large jets, the noise level of the pilot's cockpit is much higher than that of the passenger compartment. The pilot has experienced occupational diseases that often suffer from hearing loss after several years of flight experience. The performance is that the pilot cannot hear clearly in a noisy environment. Broadcast content of the radio station. With active noise suppression, wind noise interference can be reduced by more than 10dB. Therefore, the language communication level in the earphone can be lowered, thereby improving the listening effect.
Today, there are four professional use of active anti-noise headphones. Its manufacturers are Bose, Sennheiser, Telex and NCT. All four headphones use closed earmuffs to block external sounds to reduce noise (other than the lowest frequency noise, other noise can be reduced), using active noise suppression methods to reduce the ambient noise in the lowest frequency range.
Is the earmuffs of the earphones open or closed? It should be said that there is a good time. The earmuffs are open-type earphones, which are comfortable to wear, and the earmuffs are closed-type earphones, which can perform passive anti-noise, especially in the frequency range above the intermediate frequency and the intermediate frequency, and also can perform good low frequency for the continuous sound. Noise reduction. In high noise environments where the acoustic energy exceeds 100 Hz, closed earmuff headphones must be used.
Most professional anti-noise headphones come with a controller that can work for a long time, a battery pack and a rechargeable battery. As far as the headphones themselves are concerned, professional headphones are more sturdy and heavier than consumer headphones. All professional headphones have a fixed microphone or a movable microphone.
Base's anti-noise headphones look big and bulky at first glance, but they are very comfortable to wear. The performance is excellent, although the battery pack is a burden, it must be carried with you, but wearing it for a few hours is not enough, it is highly desirable to use this headset for inline communication in a noisy environment. This type of earphone has the disadvantage that the total noise attenuation of the earmuffs and active noise suppression seems unnatural, giving the first impression that it is like walking into the anechoic chamber.
The civil aviation anti-noise earphone produced by Telex has good working performance, but it is too heavy and uncomfortable to carry. The circuit also produces a humming sound. Although the sound is very low, the passive attenuation of the earmuff is high. This kind of snoring can still be heard. This headset is suitable for inline communication, and this year Telex has introduced a lighter weight anti-noise headset.
Sennheiser's anti-noise headphones have good noise immunity and performance, and the headphones are also rugged for use in high noise environments.
NCT initially produced Noisebuster consumer headphones, and recently introduced the Proactive2000/3000 series of industrial anti-noise headphones. There are ten models, some with free-moving microphones, some with helmets, and 2000 series headphones. Closed, lightweight, suitable for use in moderately noisy environments, 3000 Series headphones are suitable for use in high noise environments, 2000/3000 series industrial headphones have a very light battery pack and a signal processor for long hours of operation.
Active noise immunity can be used to reduce the noise of continuous sound, such as jets, diesels, fans and other noises that move at constant speed. Because the music signal changes too fast, it can only reduce noise through closed headphones, but can not reduce noise through electronic circuits. The general closed earphones will give people a feeling of ear suffocation, ear canal fever, and wear for a long time. Very uncomfortable. Professional closed earphones, especially earphones for musicians who work exclusively in concert halls, with small sound holes, which can pass signals across the entire audio range and evenly attenuate the signal. Otherwise, An excessively low bass will be unevenly distributed, while intermediate and high frequency signals will gradually block.
If the external noise is very large or deep, all open consumer headphones will be overdriven. For example, headphones made by Koss in Italy are particularly unsuitable for use when the aircraft takes off and land, because the earphone components will shake with the rise and fall. The wearer feels very uncomfortable.
All of the headphones are more or less a sense of oppression, perhaps because the speaker components are not working in their linear range, and the pressure is most pronounced in the high-level ultra-low frequency conditions. But expensive aerospace headsets are less obvious under such conditions, and consumer headphones, after long-term use, give people an unbearable sense of oppression, which is a real problem to be solved. problem.
By the way, the price of headphones is a problem. In just a few years ago, the price of professional active anti-noise headphones was $1,000, and NCT’s consumer headphones were also between $300 and $500, but now there is competition. Sexual branded consumer headphones are well below $200.
The use of active anti-adaptive technology in headphones is only the beginning of this technology. Although the cost of active anti-noise is about five times higher than the cost of conventional mufflers, under certain conditions, this may not be very important. Because the speaker used for active noise immunity does not block engine exhaust, this can save roughly 5% of fuel costs. If an active noise-canceling muffler can be designed, the added cost of active noise immunity is much smaller than that of a conventional muffler, not to mention the energy saved during vehicle operation.
Xbox Series X Vertical Stand Cooling Fan
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Design for X-box SX / SS game console and controller . Including 3 USB hubs,which can expand USB functions and easy to use
*Includes two charging docks, which can charge two X-box SX / SS controllers at the same time.
*With charging indicator function.When the indicator light is blue, it means it is fully charged or empty; if the indicator light is red, it means it is charging.
*Includes two cooling fans, 3000RPN, with a power button, which can quickly and effectively cool the x-box SX/SS game console. *The bracket can hold up to 11 game disc boxes. |
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Product Name
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Vertical Stand for Xbox Series X Game Console with 3USB BUB
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weight
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575g
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Input
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DC5V1A
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Output
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500mA
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Product color
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Black
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Product size
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20.5*4*36.3cm
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OEM/ODM
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warmly welcome
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Advatage
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100 QC test before shipping
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Delivery Method
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DHL,TNT,UPS , FEDEX ETC
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Xbox Series X Vertical Stand Cooling Fan,Xbox Series X Vertical Stand,Xbox Series X Cooling Fan Station,X- Series X Cooling Fan
Shenzhen GEME electronics Co,.Ltd , https://www.gemeelectparts.com