Active and passive noise cancellation. Noise. It’s all around us. Whether it’s a crying baby, the hum of an air conditioner, or the lively babbling of your office colleagues. A quiet place to work or play becomes a truly valuable commodity. Noise-canceling technology can bring Zen back into your life.
How Does Noise Cancellation Work?
The question is, how does noise reduction work? Let’s take a look at the principles of this technology so you can make an informed choice when purchasing your own noise-canceling equipment.
A (very) basic overview of sound
Sound is energy traveling as a wave through some form of matter. We usually hear sound transmitted through the air.
For example, a guitar string vibrates in the air, breaking air molecules. These molecules collide with their neighbors and so on. When a wave moving through the air hits the eardrums, it moves them at the same frequency as a guitar string.
Your brain converts this movement into electrical signals, which you then perceive as sound. This is a very simplified explanation of what sound is, but it’s the last thing you need to know to understand noise cancellation.
A (very) basic overview of audio combat
The wave has different properties. It has a frequency that indicates how often the wave goes through a complete cycle.
Let’s use our guitar string again as an example. Frequency is how quickly the string goes through one full vibration.
We perceive high-frequency sound as high. Low-frequency sound is more bass sound. Besides frequency, waves also have amplitude. This is the height of the peak of the wave. Further, the wave also has a phase. This is the position of the peaks and troughs of the wave.
If you generate a sound wave with the same amplitude but with the opposite phase (the peaks are where the troughs of another wave are), it causes destructive interference. The two waves essentially neutralize each other.
This can be done on a large scale when you need to have as much energy in your sound generator as the original sound itself. However, if you want to suppress noise for just one person, you don’t need much power at all, and this is where noise-canceling headphones come in handy.
Noise-canceling headphones are a technical marvel. There are microphones on the outside of the headphones that measure ambient noise outside of the headphones. This sound is analyzed by the onboard electronics using a mathematical algorithm. Each headphone manufacturer has its own secret sauce algorithm, each of which works with a different level of effectiveness.
Sony Noise Canceling Headphones WH1000XM3
The algorithm is used to calculate the anti-noise wave required to destructively affect the surrounding noise in the place where you are. Then a device known as a transducer, which is essentially a type of speaker, generates an anti-noise wave.
Ultimately, when you turn on the noise canceling function, you are suddenly enveloped in (almost) silence. This allows you to enjoy the sound with much more fidelity, or simply enjoy peace and quiet.
Active and passive noise cancellation
The process we just described is usually referred to in product specifications as active noise canceling or something similar. Confusingly, some headphones claim to have so-called “passive” noise canceling.
It is very important not to confuse these two functions. In fact, there is no passive noise cancellation. In fact, the term means that this pair of headphones was designed to block out sound using plain old soundproofing.
This means that the materials and construction of the headphones insulate you from outside noise to some extent. From this point of view, putting your fingers in your ears also means passive noise cancellation.
There is a lot to be said for headphones that provide excellent sound isolation, but linking it to noise cancellation is kind of a marketing knack.
Active noise cancellation limits
Current Active Noise Cancellation technology cannot completely block out noise. They work incredibly well when it comes to constant, predictable sources of noise. Imagine a jet engine, the hum of an air conditioner, or a refrigerator compressor. Modern active noise cancellation removes this type of sound incredibly well.
Conversely, sudden, unpredictable sounds are a much bigger problem. This usually includes loud human conversations, breaking a glass cup, or any other noise that the algorithm does not have time to analyze. At the same time, new advanced systems with faster processors and more sophisticated algorithms are also starting to deal with these types of noise.
Electronic Awesafe Shooting Headphones
One interesting example of such specialized active noise-canceling technology is electronic headphones used when shooting rifles, pistols, and other firearms.
These headphones use passive sound isolation to block out all sounds, just like regular shooting headphones. However, they do have external microphones that let sound through to your surroundings to maintain situational awareness.
So you can easily talk to the other person. However, the maximum volume of all sound around you is maintained at a comfortable maximum.
These systems can often provide the directional sound as well as amplify quiet sounds while suppressing gunfire. It’s not exactly the same technology as conventional noise-canceling headphones, but it’s closely related.
AI noise removal
A fairly new development is the use of artificial intelligence technology to remove unwanted noise from the audio signal. Unfortunately, this cannot yet happen in real-time, so it is ineffective for noise cancellation. What it is very good at is removing noise from the microphone signal.
For example, if you are trying to reach someone on Skype or record a voice in a noisy environment, it may be difficult for the other person to understand what you are saying.
Using artificial intelligence, this audio stream can be analyzed and removed from everything except your voice.
For example, the Nvidia RTX Voice app uses dedicated deep learning hardware in its RTX graphics cards to process microphone audio. So, whether someone is typing on a keyboard, vacuuming the floor, or doing construction work, all of this will not be heard by your audience. You can see a demo of this incredible technology here.
Since there is enough time for the AI ?? to do its job between when you speak into the microphone and the other person can hear the sound, there is no problem in terms of real-time constraints. Perhaps with advances in technology, these ultra-efficient artificial intelligence noise removal techniques will also work as a form of noise cancellation in headphones.
Noise canceling microphones
Moving on from headphones, another place where this kind of technology can be very useful for most people, especially now that many of us rely on telecommuting, is in noise-canceling microphones.
Once again, even though the marketing language uses the term “noise canceling”, these microphones do not generate noise to prevent interference from the noise source. Instead, they take the whole sound and then apply the same noise identification algorithm to it. Remove it from the input audio stream before transmission.
You even get built-in AI-powered microphone noise canceling solutions like this ASUS adapter Plug it into a USB port, plug a headset into it, and the small electronic brain inside will eliminate unwanted noise, leaving only your crystal clear voice.
sound of silence
You don’t notice how much the constant noise of modern life bothers you until you can block it out. With a pair of good noise-canceling headphones on, you can feel like a refreshing breeze blowing your low anxiety away.
Now that you know how noise cancellation works, you can make more informed decisions about your chosen noise-canceling kit. If you buy the right things, you will find that silence is indeed the best music you can get.
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