What types of ANC headphones are there? from ycbing's blog

Active Noise Cancellation (ANC) has become a popular feature in music headphones. Many headphones now have ANC,  Hybrid Active Noise Cancelling Headphones，but not all headphones are created equal.

Three Active Noise Cancellation

Hybrid Active Noise Cancellation (microphones inside and outside the ear cups)

As you can guess, the hybrid approach is the best of both worlds, combining feedforward and feedback ANC by placing a microphone inside and outside the ear cup.

Feedforward Active Noise Cancellation (Out-of-Ear Microphone)

In a feed-forward setup, the microphone is placed outside the earcup. Microphones hear noise before humans. The ANC then processes the noise and creates anti-noise and sends the resulting signal to the headphone speakers.

Feedback Active Noise Cancellation (In-Ear Microphone)

In a feedback setup, the microphone is located inside the earcup and in front of the speaker, so it can hear the resulting signal in exactly the same way as the listener.

like：

Which is better, ANC headphones or PNC headphones?   

What is the difference between hybrid noise reduction and anc    

Why do headphones have noise floor?