The importance of noise-canceling headphones, I believe that friends who have used them have deeply experienced. As one of the greatest inventions of the new era, noise-cancelling headphones are already one of the must-haves for urban life. On the one hand, noise-cancelling headphones can bring us an extremely rare moment of peace in city life, allowing us to better enjoy the music we like. On the other hand, the ability of noise-canceling headphones to isolate and eliminate noise can also protect our health from a physiological and psychological point of view.
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But the problem also arises, the headphone brand only said that noise-canceling headphones can protect hearing when advertising, but at the same time, medical common sense tells us that us us use headphones for a long time is harmful to hearing. And the active noise-canceling headphones work by playing inverted sound waves, which doesn't make us hear double the noise? Do noise-cancelling headphones really protect our hearing?
Obviously, we're not the only ones who have the same questions about noise-cancelling headphones. In CCTV's weekly quality report, the program team conducted an investigation into the chaos of noise-canceling headphones on the market, and the results were equally shocking: some brands of noise-canceling headphones really have the possibility of damaging users' hearing.
So as the first barrier of the user's ear, how does the noise-canceling headset affect our hearing?
First, the harm of noise to hearing
To talk about how noise-canceling headphones protect hearing, we have to start from the harm of noise to hearing. As we all know, sound waves vibrate through the air and travel from the external ear canal to our eardrum (eardrum), and the eardrum captures the air vibration and conducts it from the ossicles to the cochlea. But contrary to what most people understand, noise doesn't affect our hearing by damaging the elasticity of the eardrum, it's the auditory hair cells inside our cochlea that really affect it. Behind these auditory hair cells is our nervous system, and the sounds of the outside world are also transmitted by them. Noise affects the normal work of auditory hair cells, and is more likely to cause irreversible damage to auditory hair cells, thus affecting our hearing level.
This is also the main reason why in the era of noise-cancelling headphones, we have to lower the volume to protect our hearing. Auditory hair cells are sensitive and have a limited number and lifespan. Long-term exposure to noise or unhealthy ear habits can increase the workload of auditory hair cells, shorten the overall lifespan, and thus damage hearing.
Second, the protection principle of noise-canceling headphones
Knowing the principle of noise damage to hearing, then we can start from the principle and analyze how noise-canceling headphones protect our hearing. Early noise-canceling headphones we do not talk about it for the time being, modern noise-canceling headphones can be roughly divided into active noise reduction and passive noise reduction two working principles from the principle. Of course, the two working principles do not conflict in principle, so headphone products that use active noise reduction schemes often take into account the function of passive noise reduction.
Let's start with passive noise reduction: In essence, passive noise reduction is not fundamentally different from covering the ears, mainly from the perspective of sound transmission and sound reception. As I said, sound waves travel through air vibrations, so as long as we block the sound waves before they reach the ear, we can easily isolate the noise hazards. Specific to headphone products, in the past, in the noise environment, in order to hear the contents of the headphones clearly, we often needed to adjust the headphone volume to a very large level.
Although we turn headphones up louder to cover the volume around us, higher volume levels can still cause damage to our auditory hair cells. Passive noise-cancelling headphones isolate noise from the headphones, allowing us to hear clearly what is playing inside the headphones at a lower volume, which is how passive noise-canceling headphones protect hearing.
The working principle of active noise-canceling headphones is different from that of passive noise-canceling headphones, which capture the surrounding sound waves outside the principle of passive noise reduction, and after processing, the noise is played together with the audio content in the opposite phase, and the external noise and the inverted sound waves in the played audio cancel each other out, so that the final presented synthetic sound wave presents the original appearance of the audio.
Since sound waves in opposite phases do not stack, people don't have to worry about hearing double the noise. Under the action of active noise reduction, users can reduce noise interference without raising the volume, and can clearly hear the playback content of the headphones with a lower volume, so as to achieve the purpose of protecting hearing.
That's right, in the case of content playing inside the headphones, both active noise-canceling and passive noise-canceling headphones protect hearing by reducing noise intake. However, if the user plays music in the headphones, whether the noise-canceling headphones can play a role in protecting the hearing depends entirely on the user's own volume.
Third, the potential harm of unqualified noise-canceling headphones
Since hearing health is linked to volume levels, why do substandard noise-cancelling headphones cause damage to our hearing? At the end of the day, it has to do with our ear habits. Since there is no relevant national standard for noise-canceling headphones in China, many domestic noise-canceling headphones choose to use edge balls, or even false propaganda, to exaggerate their "noise reduction" effect:
For example, some brands confuse the concept of active noise reduction and passive noise reduction, and suggest that their headphone products have excellent noise reduction capabilities with active noise reduction. Some brands confuse the concept of noise reduction and promote upstream noise reduction (microphone captures your own voice and sends it to the other party) as downlink noise reduction (noise reduction when playing audio content). Some brands confuse the noise reduction ability of their headphones at different frequencies of noise, and publicize the noise suppression ability for specific frequencies as the standard noise reduction ability of headphones.
Because the noise reduction level of headphones is not up to standard, consumers have to involuntarily increase the playback volume of headphones in order to hear the sound played in the headphones when using such headphones, which unconsciously becomes the culprit of permanent damage to their hearing, and it is too late when they perceive that their hearing is impaired.
According to a survey released by the World Health Organization in 2019, nearly 50% (1.1 billion) of people aged 12-35 years worldwide are at risk of hearing loss, and nearly 5% of the global population currently faces degenerative hearing loss, which is directly linked to poor ear habits. And those noise-canceling headphones that are not on the right board not only fail to protect our hearing, but have become a health vulnerability for our hearing safety. In this regard, both the relevant departments and consumers must have their own reflections.
First of all, the relevant departments need to introduce corresponding national mandatory standards, clarify the type of noise-canceling headphones, noise-canceling ability labels and test methods, so that noise-canceling headphones have corresponding standards to follow, and eliminate the possibility of indiscriminate charging. Secondly, consumers should also pay attention to their hearing level, understand the corresponding common sense of ear use, and not let themselves become the culprit behind the future deafness.
Just like protecting your eyesight, protecting your hearing is a long struggle. At this stage, the domestic public has no sound understanding of hearing health, which means that all parties concerned still have room for efforts. In order for us to enjoy our favorite music in the future, I still hope that everyone will pay more attention to hearing health and conduct regular special tests on hearing like regular physical examinations. After all, the ears grow on their own, and now they cherish their hearing or abuse their ears, and ultimately they have to be responsible for themselves.
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