Hybrid noise-cancellation is a type of active noise-cancellation: it relies on microphones to seek out ambient noises and then cancel them out. But where it’s common for most active noise-canceling headphone designs opt to place microphones solely on the outside or solely on the inside of the earcups, hybrid noise-canceling headphones have both.
Generally, active noise-canceling headphones with internal microphones tend to sound great, but have less-than-optimal noise-cancellation powers. This is because the microphones hear when the listener hears (since the mics are on the inside), and they know exactly what sounds to block out without polluting the actual music that is attempting to reach your ears. Unfortunately, this approach typically can’t handle louder noises and higher frequencies, however, so the noise-cancellation isn’t as good.
With active noise-canceling headphones that have external microphones, the opposite is true. Since the mics are on the outside, they tend to block out a wider range of frequencies and can do better with generally louder sounds. The downside is that they typically create more “anti-noise” and this can negatively impact sound quality.
This isn’t an exact science, of course, and there are a ton of different factors to consider. Every headphone manufacturer has its own combination of materials, speaker drivers, connectivity and (most importantly) noise-canceling technology. Hybrid noise-canceling headphones, which utilize both internal and external microphones, should be best of both worlds — excellent sound quality and good noise cancellation — but it doesn’t always work out that way.
Well you may have already. Many of today’s noise-canceling headphones are actually hybrid noise-canceling headphones — even though they don’t advertise it. Companies like Bose and Sony don’t tell us much about how their noise-canceling technology works — it’s their secret sauce, after all — but we can guess a few things. Many noise-canceling headphones these days allow you to adjust the noise-cancellation between “high” and “low” settings, and because most of these headphones probably use hybrid noise-cancellation, they likely switch between using internal and external microphones. On “low” noise cancellation, the headphones likely use internal microphones because the audio quality is likely to be better. And on “high” noise cancellation, it’s likely that the headphones use their external microphones so that the ANC is most powerful.
In theory, yes. As stated above, the issue is that most of today’s best active noise-canceling headphones are actually really hybrid noise-canceling headphones, they just aren’t advertised as such. And because different headphones have different processors and different acoustic drivers, and come in different styles and are made from different materials, it murkys the waters a bit.