Nên mua tai nghe Bluetooth nào tốt nhất? Cần lưu ý gì?

The era of wireless headphones is gradually taking the throne and is expected to become a new trend. However, their quality and safety are always a question for users.

Wireless Technology

Wireless technology is gradually changing our world from radio and TV to cell phones and many other devices that use wireless transmission. Wireless technology offers unprecedented convenience and benefits. To be honest, wireless technology also has its drawbacks, and that is the radio frequency from electronic devices that travels in all directions, not just to the receiver.

Even now, as you sit somewhere with your smartphone in hand reading these lines, several different Wi-Fi network signals are hitting your body. On top of that, there are hundreds of other weaker types of signals, such as FM/AM broadcasts, satellite and various other broadcasts, surrounding us every moment of every day.

We may have tried to avoid the signal sources, but smartphones and wireless headsets are always nearby. We use wireless headphones so we can drive hands-free or talk on the go. The new definition of wireless headphones was truly redefined when Apple introduced AirPods and made it a phenomenon for years.

Wireless headphones are great accessories, but is it worth the daily exposure to EMFs (electromagnetic fields)? Let’s find out together!

How do wireless headphones work?

No matter what brand of wireless headphones you choose, they all work by way of Bluetooth. This means that the user must connect the headset to a device that supports this method. Bluetooth is not a new technology, it is simply a widely adopted standard for transmitting radio frequencies over short distances.

The Bluetooth antenna on the AirPods is located along the battery body of each headset

The Bluetooth frequency range operates between 2.4 GHz and 2.4835 GHz, about the same as a microwave oven (2.45 GHz). But of course the difference is in the power, with microwaves operating between 600 and 1200 W, while Bluetooth headsets are just Class 2 transmitters. That is, they can transmit signals within 10 meters and work. The maximum power to work is 2.5 milliwatts, which is 240,000 lower than 600 watts. In other words, it would take months for a wireless headset to emit the amount of energy a microwave oven produces in one minute.

Specific Absorption Rate (SAR) – What does Specific Absorption Rate mean?

First of all, SAR stands for Specific Absorption Rate, which is a measurement of how many frequencies of electromagnetic field frequencies are absorbed by the body, such as cell phones. Cell phones or wireless headsets, etc. SAR is measured in watts per kilogram (W/kg) and is determined to be safe by regulatory authorities, and a wireless device is also determined to be safe for that measurement to be zero.

Unlike other scientific measurements, SAR has several “asterisks.” EMF (electromagnetic field) waves do not propagate uniformly, so this measurement represents only the average energy absorbed by a given tissue. In the US, the FCC has set a limit of 1.6W/kg for cell phones, which is measured at a point within 1g of the tissue that absorbs the most energy. Europe follows the International Electrotechnical Commission’s standard that every 10g less than 2 W/kg is a safe tissue. Each device must be tested individually for each standard.

Are wireless headphones good? Devices used to test SAR It is important to note that the FCC is inconsistent in its testing of SAR. It was designed in 1989 and used to measure a prosthetic head equivalent to a human head (6.2 inches) weighing 100 kg. The human brain is illustrated by a mixture of water and electrolytes. During testing, the prosthesis is subjected to a maximum operation of 6 minutes before measurements are performed. If applied to humans in 2019, this does not indicate safety, even if it is only a test. SAR in Bluetooth headsets? said Joel Moskowitz, director of the Center for Family and Community Health at the University of California, Berkeley.” Regular use of wireless headphones can greatly increase the effects of electromagnetic waves. The body, and especially the brain. the absorption rate of Airpods is quite high because it is a Bluetooth device.” The exact SAR of AirPods is 0.581W/kg in the left ear and 0.501W/kg in the right ear, for a total of 1082W/kg when you use both ears. for comparison, the iPhone XS has a SAR of 1.19W/kg, just 10% more than AirPods. These are just theoretical numbers, and may vary in actual use.

Of course, every electronic device we use every day is considered safe, or at least the test results prove it. In the case of AirPods, if you’re really interested in the SAR index, you can check out the AirPods SAR report that Apple sent to the FCC (Federal Communications Commission).

So, are wireless headphones safe?

Dr. Moskowitz continues.” Wireless headphones are not recommended, and he himself does not use such devices because of their electromagnetic waves.” A group of more than 240 scientists worldwide has even signed an international call with the United Nations for greater regulation and protection against non-ionizing EMF exposure.

According to the call.

Electromagnetic waves affect organisms to a lesser degree than international and national regulations. Effects include increased cancer risk, cellular stress, increased harmful free radicals, genetic damage, changes in the structure and function of the reproductive system, learning and memory impairments, neurological disorders, and negative effects on overall human health.

It should be noted that the scientists’ concern is that for devices that generate electromagnetic waves at range, from Wi-Fi transmitters, the cumulative effects all around us are responsible for increased human health risks rather than any utility.

For wireless headphones, there is no convincing evidence that they are harmful to humans, as no studies have been conducted on the long-term effects of wireless headphones. The electromagnetic waves of headphones are too weak to have any noticeable effect on the human body, which means we can ignore the effects of wireless headphones and use them without worry

In terms of manufacturers, Apple, Samsung and Bose when asked about the true safety of their wireless headphones, but only Samsung answered. The company said that it has met all the necessary regulations, that electromagnetic wave tests are strictly adhered to and that they are safe for everyday use. Regarding the SAR of Galaxy Buds, Samsung added: “Our wireless headphones are designed to minimize absorption rates and do not produce significant RF exposure even at full power”.

In the end, wireless headphones may not be bad for our health, but they certainly don’t make us better. As smartphones have become ubiquitous and irreplaceable, the convenience of using wireless headphones seems like a perfectly understandable choice to use them. We can consider deciding which technology to use, and hopefully the authorities will provide clearer and more convincing data so that users like us can make an informed decision. Transparency.