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There’s tons of tech packed into your smartphone, from processors to modems, and even dedicated parts to monitor your phone’s gyroscope sensors. Audio hardware is heavily integrated into mobile today too, but an overlooked yet essential technology packed into all our phones is noise cancelling capabilities.
What is noise cancellation?
It’s in the name— this technology is designed to cancel out background noise so you can hear more clearly or
Noise-cancelling headphones are headphones that reduce unwanted ambient sounds using active noise control. This is distinct from passive headphones which, if they reduce ambient sounds at all, use techniques such as soundproofing.
Types of Noise Canceling Headphones
1. Passive Noise Canceling Headphones
These headphones block out sounds by making use of various materials that can help reduce the amount of sound that will reach your ears aside from the sounds coming directly from your headphones. The materials of the headphones will be responsible in blocking out the sound.
2. Active Noise Canceling Headphones
These headphones can also block out outside noises that may hinder you from listening properly to music but they are built differently from other headphones. Active headphones usually have a structure that can be turned on in order to cancel out the sounds.
MECHANISM IN NOISE CANCELLATION
First, a primer on how it works. One of the basic laws of physics is that waveforms of equal amplitude and opposite phase cancel out. In other words, if I take at an instance of a wave with a peak of 1 volt and combine that with an inverted wave with a voltage of -1V, I end up with 0 volts. The two cancel each other out. With noise cancellation, the theory is that if we can capture the background noise with a mic, invert the signal phase by multiplying it by -1, and then adding that back to our original signal, we can cancel out the noise. Simple enough.
The theory breaks down a little when we leave the theoretical and enter the real world. Microphones are imperfect, electronic conversion introduces noise of its own, and the phase of the cancellation waveform leaving the speaker might not perfectly line-up with the phase of the noise once it reaches your ear. These systems need to be finely tuned, but even then you won’t ever see 100 percent cancellation. Instead, between -20 and -30 dB of noise reduction is quite common, which cuts the background volume anywhere from 1/16th to 1/32nd. A considerable amount.
Narrower bandwidths allow for more attenuation or noise reduction, while wider bandwidths cover more frequencies but can’t reduce the amplitude as much. This is important to consider when understanding the pros and cons of say, trying to filter out all the audible background noise or just removing the noise around the frequencies of the human voice.
Inside your phone
If you still make calls on your smartphone, you’ll hopefully have noticed that it’s pretty easy to hear what’s being said, and that you’re coming through nice and clear on the other end. Improvements in call quality have a bit to do with this, but crystal clear calls are also down to your phone employing active noise cancellation to remove some of the background noise when you hold your phone up to your ear. Phones have been employing this technology for a number of years, and it keeps on improving.
Noise cancellation is essential for making sure you can hear and be heard while taking calls in busy environments.
In addition to the main microphone for recording voice, your smartphone comes equipped with additional microphones to assist with noise cancellation. The recordings from these mics can be used in the way described above, canceling out background noise around you. This same background information can also be used to cancel out the noise that’s picked up by the voice mic you’re speaking into, but inverting the noise signal and combining it before bending the voice packet off over your network.
In addition to noise cancelation, information picked up from secondary microphones can also be used to automatically adjust call volume based on background noise levels and attempt to filter out howling wind. Many of these features are packed into smartphone SoCs from the likes of Qualcomm and others, making them readily available in most smartphones.
Multi-microphone setups serve another purpose too: localized voice for smart assistants. Multi-microphones are essential for locating the direction of an incoming voice. This information can then be used to discern what’s background noise, even if it’s other voices or a TV, which is then filtered out to provide the cleanest possible source for the voice recognition algorithms.
In your accessories
Clearly then, the same applies to smart home products like the Google Home and Amazon Echo. As well as directional speech detection, these devices employ similar noise reduction and echo cancellation techniques to what you’ll find in your smartphone. Alexa implements up to 6 omnidirectional microphones in its design, offering better speech detection and noise reduction characteristics than your typical smartphone.
Popular smartphone accessories from wireless headphones to smart home assistants rely on this technology.
More About Noise Canceling Headphones
There are some people who say that the sounds may not be that good whenever they are using noise canceling headphones mainly because the sounds tend to be muffled. The sound quality may be affected but some people who have used noise canceling headphones that are made of great quality do not report this issue. Another problem that people may encounter when purchasing noise canceling headphones is they tend to be more expensive than regular ones. Some noise canceling headphones are not that effective in blocking out noise as well. It will always be best to consider the quality of the headphones that you are going to purchase beforehand.
There are also other benefits that can be received when using noise canceling headphones such as the following:
{:14_35:}Stops Possible Bouts of Fatigue – There are some people who tend to feel nauseous whenever they travel but the use of noise canceling headphones can help stop that. The main reason why people suffer from fatigue is because of the low frequency noise that people become exposed to for long periods of time.
{:14_35:}Cancels Noise Appropriately – There will be moments when you do not want to listen to other noises especially when what you have to listen to is important.
{:14_35:}Sound Need Not Be Too Loud – There is a big chance that you would like to listen to music that will not break your eardrums. When you are using other headphones, you may have to increase the sound because you cannot hear anything else but with noise canceling headphones, this is not required anymore.
Ideal for Studying – If you need headphones that will allow you to just focus on music and what you are studying or reading, noise canceling headphones may be the best option.
{:14_35:}Improves Listening Experience – Since you will only be hearing what you are required to listen to, your experience with listening to music can be greatly improved.
:hug:Searching for the right noise canceling headphones can be complicated but you have to remember that if you would like to get its benefits, you can always choose it over all the regular headphones available. Consider its mechanism and the various products available so you can choose the right one for you.
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发表于 2018-01-03 01:18:52
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