On many shopping software, a search for "headphones", you may search for headphones with different prices, there are hundreds of thousands of yuan, there are also 9 yuan 9 free shipping, and even less than 2 yuan can also be free shipping headphones, such a price can be said to be so cheap that it is a little suspicious.
Image source: Screenshot of an e-commerce platform
If you search the Internet, you can even find a lot of news about headphone leakage. Can the headphones with free shipping really work? Will there be leakage with such headphones? Does it hurt the ears? Let's talk about the relationship between headphones and hearing.
Cheap headphones leak electricity and hurt your ears?
First of all, it is necessary to distinguish here, the price of headphones is cheap, it may be the promotion behavior of the merchant, and of course, it may also be the headphones sold by the store that are not of standard quality.
So how do we as consumers distinguish between them?
In fact, it is very simple, as long as you see whether there is a "quality inspection certificate" on the earphone packaging box or in the packaging box.
According to Article 27 of the Product Quality Law of the People's Republic of China issued by our country in July 2000, all products or their packaging should have a product quality inspection certificate.
No matter how cheap the headphones sold in the online store are, they must also have a product quality inspection certificate.
If there is no certificate, then such goods are likely not to be produced by regular manufacturers. If you really buy it, it is also recommended not to use it to avoid leakage. And if you buy such a product, consumers can directly call 12315 or protect their rights on the official website of 12315.
As long as the headphones you buy have a product quality inspection certificate, you can usually use them with confidence. Of course, for headphones with free shipping for 2 yuan or 9 yuan for 9 free shipping, you shouldn't have too high expectations in terms of sound quality.
However, some people may find that even if the headphones are of acceptable quality, they may have a faint "electric ear" feeling during use. This "electric ear" may not be due to the leakage of the earphones, but the static electricity generated by the earphones after rubbing against clothes and hair.
Apple's official website explains headphones and static electricity
For example, there is also a special reminder of static electricity on the earphones on Apple's official website, for this slight "electric ear" phenomenon, don't worry too much, and generally add a sponge case to the earphones to solve part of the static electricity problem.
Compared with headphone static electricity, when listening to music, headphone volume is more likely to damage hearing. Such damage is often insidious and irreversible.
Volume and hearing loss
To understand how excessive volume can damage the ear, we need to first understand the structure of the ear.
After the sound waves are transmitted to the inside of our ears, a structure called "hair cells" in the cochlea can sense these vibrations and convert these vibrations into nerve signals that are transmitted to the brain, which processes them and we hear the sound.
However, these hair cells are fragile, and if the vibration is too strong, the hair cells may be damaged. For example, if you hear a loud noise suddenly, you may temporarily lose your hearing or have a burst of tinnitus that will take a while to recover. However, if the noise is particularly loud or if it is exposed to loud noise for a long time, the hair cells may be permanently damaged and die.
Another characteristic of hair cells is that they cannot regenerate after death. That is, the hearing damage caused by hair cell death is irreversible.
In contrast, the hair cells responsible for sensing high-frequency sounds are more susceptible to damage, so people generally lose hearing from high-frequency sounds first. For example, the very sharp "sizzle" produced when the microwave oven or induction cooker is working, or the "sizzle" sound made when the old transistor TV or monitor is turned on.
However, these sounds have almost no impact on daily life, so it is often difficult for people to notice in the early stages of hearing loss, and it is even more difficult for people to realize that their ear habits are unhealthy.
How loud can it hurt your ears?
So how loud is the sound that damages hearing? It depends on the volume and the amount of time exposed to that volume.
The World Health Organization has given a safe listening time at different volumes.
Safe listening time and corresponding scenarios at different sound intensities. Image information source: WHO official website
For example, the volume of our normal conversation is about 60 decibels. As long as this volume is not exceeded, the safe listening time per week is unlimited, i.e. there is no damage to our hearing.
When taking the bus and subway, the noise in the car is about 85 decibels, and the exposure time is less than 12.5 hours per week, which averages about 1 hour and 40 minutes per day.
But beware, after getting on the subway or bus, you may unconsciously turn up the volume. This is because if you want to hear the sound in your headphones more clearly, you need to have to make the sound in your headphones louder than the background noise.
How much you can increase varies from person to person. We can refer to a 2016 study published in Advances in Experimental Medicine and Biology (Adv Exp Med Biol.), which showed that people can understand semantics more clearly when the volume of human speech is more than 6 decibels higher than background noise.
So if you want to voice chat with someone on a bus with a background noise of 85 decibels, or if you want to hear the details of the music, it's easy to turn up the volume to 90 decibels, or even above 95 decibels.
Another study published in the International Journal of Audiology found that when the background noise is at 75 decibels, people will already turn up the headphone volume to 90~95 decibels.
Background noise and the intensity of sound that people tend to use. Image source: Reference[3]
At 95 decibels, the time spent safely listening is 1 hour and 15 minutes per week, which is about 10 minutes a day on average, and most people can commute much longer than that. So, listening to music on the bus and subway to commute to work is likely to have exceeded the "safe listening time".
In addition, a 2017 article published in Noise Health looked at how young people in Sweden listened to music, and about 10% of young people listened to music at a loud volume, reaching 90 to 100 decibels. Even when I sleep, I listen to music with such a loud voice.
There is no doubt that this can damage hearing.
How to protect our ears?
According to the above, it is actually very simple to protect your hearing, as long as you pay attention to controlling the volume of the headphones when listening to music or making phone calls.
But the question is, how do we know how loud the music we listen to?
In fact, many mobile phones will have their own hearing protection function. When the volume is adjusted too much, a prompt will automatically pop up. At the same time, you can also directly adjust the safety upper limit, and automatically lower the volume when the headphone volume exceeds the upper limit.
It is possible to set the sound to reduce the super-high. Image credit: Courtesy of the author
In addition, the volume of the headphones can also be counted in many mobile phones. For example, in the health module of the Apple mobile phone, there is such a function, you can see what the headphone volume is when listening to music every day, and whether it exceeds the weekly "safe listening time".
Headphone volume statistics. Image credit: Courtesy of the author
In addition, if you don't have such a feature in your phone, you can also refer to the World Health Organization's "60-60-60 rule", which is "no more than 60% of the maximum volume, no more than 60 minutes of single use of the headphones, and no more than 60 decibels around you." ”
If you want to enjoy your own music time while commuting, you can also consider using active noise cancelling headphones.
Most earbuds and in-ear headphones are passive noise-cancelling headphones, that is, they block external noise by plugging the earphones into the ear, but the blocking effect is relatively limited.
Active noise cancellation is when the headphones actively emit sound waves in the opposite direction to reduce the noise of the surrounding environment.
Of course, the disadvantage of active noise cancelling headphones is also obvious, that is, they are expensive, and it is unlikely that headphones with 9.9 free shipping will have such a function. And when using active noise cancelling headphones, you must use active noise cancelling headphones according to the occasion, walking on the road, or when cycling, try not to use active noise cancelling headphones, otherwise you may not be able to hear the horns of the surrounding cars clearly, and then danger occurs.
After all, hearing and driving safety are important!
bibliography
[1] Official website of the World Health Organization:
https://www.who.int/zh/news-room/questions-and-answers/item/deafness-and-hearing-loss-safe-listening
[2] Whitmer, W. M., McShefferty, D., & Akeroyd, M. A. (2016). On Detectable and Meaningful Speech-Intelligibility Benefits. Advances in experimental medicine and biology, 894, 447–455. https://doi.org/10.1007/978-3-319-25474-6_47
[3] Jiang W, Zhao F, Guderley N, Manchaiah V. Daily music exposure dose and hearing problems using personal listening devices in adolescents and young adults: A systematic review. Int J Audiol. 2016; 55(4):197-205. doi: 10.3109/14992027.2015.1122237. Epub 2016 Jan 15. PMID: 26768911.
[4] Widen SE, Båsjö S, Möller C, Kähäri K. Headphone listening habits and hearing thresholds in swedish adolescents. Noise Health. 2017 May-Jun; 19(88):125-132. doi: 10.4103/nah. NAH_65_16. PMID: 28615542; PMCID: PMC5501022.
Source: "Popular Science China" WeChat public account