A lot of people get the impression it's only cancelling where there's no speech, but it's also cancelling during speech -- just not as much. If you look at the spectrogram at the top of the demo, you can see HF noise being attenuated when there's LF speech and vice versa.
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.
I wonder if there will be progress in higher-frequency canceling given there’s an engineering reason for limiting canceling to lower frequencies. The current ANC technology makes outside speech quieter yet more intelligible, and that very much increases distraction for me.
That's true, of course. But it's much harder to actively cancel higher frequencies. This is why noise cancelling works brilliantly on an airplane (relatively low frequency background noise) but it does almost nothing to filter out the sounds of conversations around you.
I always thought it was because noise cancelling can only block repeated waves (like the sound of an engine whirring) but conversation is constant changing sound so it can’t be blocked.
The way I experience it, noise cancelling works best on low frequencies of whatever you are listening. It complements passive noise isolation, which work best for high frequencies. Voice is usually in the middle, and it tends to be less attenuated, often that's a feature: you don't want do hear background noise, but you want to hear when people talk to you.
Noise cancelling headphones are never just about cancellation, they are always a combination of both cancellation and isolation working together, and it involves a lot of tradeoffs.
While the noise cancellation is active it will attempt to neutralize (destructively interfere with) sounds from the outside, including those generated by your speaker. You could indeed adversarially engage through something like a spontaneous phase shift (so the interference will become constructive, making the resulting signal louder) or generating a frequency the ANC can't compensate.
The point is that the sum of added and reduced noise is smaller in the noise cancellation than in non-noise cancellation, unless you are in an optimized environment.
Noise cancelling cannot cancel out voices. It's designed to cancel out predictable lower frequency sounds such as fans, A/C system fans, engine rumbles and jet engine noise.
The noise cancelling system has an inherent delay in processing the sound it's listening to output an opposing waveform. Since voices are not predictable, outputting a waveform after a slight delay will just cause it to be out of sync and cancel out nothing. Maybe some ML system could do this in the future, but it would have to be absolutely perfect to not sound distractingly strange at times.
Fans on the other hand are predictable, so you can output an opposing waveform despite the processing delay because you can predict how the waveform will act after your processing delay and keep them in phase.
No, the effect is caused by the noise canceling being active, not by the noise canceling becoming active. It doesn't get more or less pronounced over time.
All noise cancellation is much better at canceling low frequency noise (like the engine on a plane) than voices, for example, which it mostly just muffles. For example, I have music playing in my house right now. If I put in my AirPod Pros and turn them on, the music gets quieter but I can still clearly hear it.
reply