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How does noise-cancellation work in Mac laptops?.

I understand how it works in Headphones or even in iPhone. But if the mics in a MacBook Air 2018, for example, are located in the same spot, what is being cancelled there? How can a plane motor or fan buzz be cancelled this way during a FaceTime call or similar?

This is set up in System Preferences > Audio "Use Ambient Noise Reduction"

Any resource explaining this?

Any help much welcome.

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The microphones are not placed in the same spot exactly!

The 2018 MacBook Air actually has 3 microphones in a sort of triangle configuration. There are two microphones aligned on the right-hand side of the laptop under the speaker grille besides the Delete and | buttons (given a US keyboard). The third microphone is underneath the Delete button itself.

In addition to their placements, the three microphones also have different orientations. If you look from the top-down, the second microphone is rotated 180 degrees when compared to the first. The third microphone is rotated 90 degrees when compared to the first.

Microphone orientation

These different placements and orientations allows signal processing algorithms to seperate ambient noise from the desired signal (to a degree).

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  • I suspect this feature largely filters out keyboard noise, though I can't test it for myself.
    – Alexander
    Commented May 12, 2019 at 2:44
  • Yes, it is also designed to filter out keyboard noise - quite important given the placement of the microphones. However this question was about ambient noise reduction specifically.
    – jksoegaard
    Commented May 12, 2019 at 8:32
  • jksoegarrd, thanks for your answer. I still wonder how the Mac can tell apart unwanted noise, such as a fan spinning over your head or voices coming from your front.
    – Antonio23249
    Commented Jun 15, 2019 at 10:25
  • I thought you wrote that you knew how it works in general, but thought that the MacBook had the mics in one place. So I’m wondering what it is you want more info on - is it just how ambient noise reduction in general you want to know more about?
    – jksoegaard
    Commented Jun 15, 2019 at 11:14

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