Active noise cancelling technology is a very important feature of the modern headphone industry. Most headphones more or less come with noise cancelling feature. Although, it is still not the standard feature, and no longer reserved for the most luxurious headphones. There are more than one type of Noise cancelling available in the headphones. Moreover, you’ll find a decent selection of earbuds and even true wireless products sporting some form of noise cancelling technology.
Furthermore, there are a lot of way to execute ANC technology. Each of which has implications for the quality and type of sound that the headset is good at cancelling. In this article, We’re going to explain the differences between these types and what they mean for your next headphone purchase.
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How does active noise cancelling work?
We’ve already covered how noise cancelling headphones work, and in a nutshell. Active Noise Cancellation (ANC) uses a noise cancelling system to reduce unwanted background noise. The system is based on microphones that “listen” to the sounds outside and inside of the earphone, an ANC chipset inverting the soundwaves and a speaker inside the earphone cancelling the outside sound by the neutralising soundwaves. A bit like taking +2 outside and adding -2 inside to make zero. The idea with noise cancellation is to record the background noise, invert the noise signal to create “anti-noise,” and then add it to your output signal, which includes your music. The anti-noise signal cancels out the actual background noise at the point it reaches your ear.
However, there are some other headphones, which affect the sound cancellation. The first one is a ambient sound signature to provide the maximum degree oF attenuation. The second one is a microphone to capture the affect noise. and the phase of the cancellation waveform leaving the headphone drivers needs to perfectly line up with the phase of the noise when it reaches your ear.
Moreover, between 20-40dB of noise reduction is quite common, which cuts the background noise level you hear to between one-quarter to one-sixteenth its original level. A considerable amount. Another key point to consider is that the sound you hear inside and outside the headphones is very different. For example, compare the passive isolation of earbuds versus closed-back headphones.
This difference in sound arrest remarkably changes the quality and capabilities of active sound cancellation between the two types of headsets. This needs the question, where do you place the microphone in the best position to capture and cancel the sound? Do headphones work best outside, inside, or maybe a little bit both?
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What is feedforward active noise cancelling?
Feedforward ANC is, arguably the simplest type of active noise cancellation. In a feedforward setup, the microphone is position outside the ear cup. The mic hears the noise before the person does. ANC then processes the noise and creates the anti-noise before sending the resulting signal to the headset speaker.
Why it’s good:
In this noise cancellation the mics recognize the noise too frequently. Thus, it has save some more time to respond and cause the anti-noise. This also means that it’s better at reducing higher-frequency noise up to 1–2 kHz.
Why it’s not so good:
There is no way to self-correct in this setup, because it never hears the sound it makes. It just assumes the listener won’t hear a sound and goes, “Well, here’s my job.” If the person places the headset incorrectly or if the sound is coming from a strange angle, this setup can accidentally amplify the sound at certain frequencies. Oops!
On top of that, feedforward ANC operates in a narrow range of frequencies. Therefore, if you focus on noise reduction at about 1 kHz, feedforward ANC may have a slight effect on lower frequencies. And because the mic is closer to the outside world, it is more sensitive to wind noise.
What is feedback active noise cancelling?
The opposite of the feedforward setup, the microphone is located inside the ear cup, or inside the wearer’s ear with earbuds. Picking the right place within the ear cup’s interior presents a new set of difficulties.
Why it’s Good
Feedback ANC monitors the sound signal, which the ear also hears, and can therefore already respond to slight variations. Feedback ANC also works with a wider frequency range than feed-forward ANC. Another advantage is that feedback ANC can still reduce noise regardless of the angle to the sound source or if the ears are not completely covered.
Why it’s not so good:
For higher frequency transmissions, feedback ANC is not as effective as feed-forward. In rare cases it can actually exacerbate background buzzing noise produced since the sensor and tweeter are so close together. Feedback ANC can also filter out too much bass as noise.
What is hybrid active noise cancelling?
Hybrid active noise cancellation features the best of both the noise cancellation. Means, it is a mixture of feedforward and feedback microphones and processing to cover all the standards.
Why it’s Good
As a result, you will have the best noise attenuation frequency response and clear bass and sound. Moreover, while maintaining the advantages of an accurate, compliant ANC, the hybrid ANC can still be used for ambient noise and sound isolation features.
Why it’s not so good:
The disadvantage is that the hybrid ANC is more expensive. Not just two microphones but these microphones need to be of high quality to avoid extra noise. Headphones also require more powerful dedicated processing hardware to handle the extra math. Developers also double all frequency and performance testing to maximize noise cancellation performance. These products make the most expensive headphones on the market, but they offer the best quality ANC around.
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Does noise cancelling really matter?
While manufacturers rarely talk about the ins and outs of their noise cancellation technology. Learning more about the three main types can help inform your purchasing decisions. If you are experiencing problems with feedback or not having a high enough frequency cancellation, you may want to switch from feedback to feedforward type. Alternatively, a noise cancellation that seems a bit out of place may be a signal to switch from feedforward to something else. While there is no automatic guarantee of quality, keeping an eye on the hybrid ANC should ensure a trouble-free quiet listening environment.
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