JohnLai
Junior Member level 3

Hello, Folks,
I am looking for a pair of Active Noise Cancellation (ANC) headphones that could cancel human speaking. But almost all headphones in the market are just cancelling the low-frequency noises such as engine or fan. I do not understand why the higher-frequency parts of human voices could not be cancelled since ear hearing spectrum just reaches 20KHz. And 20KHz is rather slow in modern circuit designs, especially in IC designs running @ GHz speed.
I would suspect that if a voice signal were inverted 180 degree phase and added back to the speaker by a feedback circuit, human voices could be cancelled as well. Could somebody please explain this to me why ANC headphones can not cancel human voices.
Thanks.
I am looking for a pair of Active Noise Cancellation (ANC) headphones that could cancel human speaking. But almost all headphones in the market are just cancelling the low-frequency noises such as engine or fan. I do not understand why the higher-frequency parts of human voices could not be cancelled since ear hearing spectrum just reaches 20KHz. And 20KHz is rather slow in modern circuit designs, especially in IC designs running @ GHz speed.
I would suspect that if a voice signal were inverted 180 degree phase and added back to the speaker by a feedback circuit, human voices could be cancelled as well. Could somebody please explain this to me why ANC headphones can not cancel human voices.
Thanks.