The phase-shifted signal from active noise canceling electronics only actually achieves physical cancellation if the signal it's attempting to cancel hasn't cha

The phase-shifted signal from active noise canceling electronics only actually achieves physical cancellation if the signal it's attempting to cancel hasn't changed. By the time the phase-shifted response to a dynamic signal like speech comes out of the speaker, the signal it's trying to cancel is gone, and there is in fact more sound coming to your ears.