Question Active noise cancellation - is white noise / hum normal what its on?

[SurroundedByQuestions]

I would like to know if it is an immanent for all ANC headphones to generate some noise / hum when this feature is turned on? Is this just how this technology works?

And if yes- are there big differences between models / manufacturers - i.e. do some headphones generate noticeably less inside noise when cancelling the outside noise? [And if yes - does then less inside noise equal to more outside noise on the account of not filtering it enough?]

 

[hang-the-9]

I don't really hear any extra noise when using my Bose Q35 headset, but at times it does send some audio noise through. Also keep in mind the noise you hear may be coming from your own ears not the headset (say some low ringing noise). How noisy the headset is would depends on the headset quality. Need to read some reviews and comments on shopping sites for specific models.

Edit.. I listed to a few ANC headsets we are testing at work, they all had a low level hum to them when ANC was on.

 

[SurroundedByQuestions]

So far I have manage to test out Bose QuietComfort 35 II Wireless Headphones and Sennheiser PXC 550-II

And both of them have this hum / noise, although different sounding from each other