How do noise cancelling headphones work? | James May's Q&A (Ep 10) | Head Squeeze

It's actually more complex than you might think!

James May's Q&A:
With his own unique spin, James May asks and answers the oddball questions we've all wondered about from 'What Exactly Is One Second?' to 'Is Invisibility Possible?'

Links:

[rtread]

Im glad james has a place to properly explain things cause we know he cant on Top Gear XD

[signas]

This guy is more interesting and engaging than a college professor. Give this man a medal!

[salles]

Tonight: James does not wear a hat, James says the word tiresome (0:12) and James adds +2 to -2 (1:35).

[ELCHAMBERINO]

I admire how knowledgable and informative you are with out all the

[ThatBritBloke]

This effect also works with light, which is just mind blowing!

[MrTenad]

Hi James, nice description and good that you explained the longitudinal pressure waves in the beginning. One minor correction though - the delay you mention (when noise cancelling is turned on) has nothing to do with electronics "measuring" the ambient noise and "coming up" with the anti-noise. Instead the slow gradual activation is a built-in feature in the electronics necessary to prevent loud pop/click sounds related to powering up the audio op-amps. There are several op-amps chained together in a noise cancelling circuitry. These op-amps must be powered on in such order that the final stage audio amplifier is activated last. That way the microphone pre-amplifiers start-up pops will not be amplified - which would result in loud and highly unpleasant pop/click sound from the headphones every time the noise cancelling feature is turned on.

If the electronics would need one or two seconds to measure the ambient noise and to calculate the anti-noise the actual ambient noise would have already reached the user's ear (keeping in mind that sound waves travel 333 meters per second and we are talking about few centimeters distances here). Or to be more blunt - if the noise cancelling circuitry would work with "delay" as you describe in your video - well, then active noise cancelling headphones just wouldn't work at all ;)

[DevilWarrior]

The photo you showed at 2:56 is from Cuba, I used to live near by.

[stefanc]

already knew this before clicking on here as i work as a live sound engineer yet i still could not resist watch it :)

[volikoto]

i just subscribed! :D but I want james may to always be the host!

[ToInfinity]

We need more James May on this channel.

[LilPolemistisXL]

WHAT DO YOU MEAN THIS ISN'T TOP GEAR?

[teatoxic]

WHAAAA?!!!! James has hes own yt channel?! how didn't i find this earlier D:<

[mrwri]

James May could do every documentary ever, and I would watch every single one.

[undeny]

Great! I've always wanted to hear James' banters to full length. He's a greater speaker to Jezza's noise cancellation :P.

[NOTTODAY]

As soon as I saw Captain Slow, I subscribed immediately.

[benpeach]

He was also in a band and is constantly smiling, so the coolest physicist ever :)

[pylonsquelch]

Watched with my Bose QC3 Noise Cancelling headphones. They worked great on the trips to and from New Zealand and Canada.

[maksuree]

one thing I've always wondered: does this mean that noise cancelling headphones reduce air pressure in your ears and protect your hearing, or does it mean that they increase the air pressure and hurt your hearing?

[BenTvHowman]

And my high school phyisics teacher told me that i was wrong when I came up with this theroy, you sir just prooved that not only was i right but in the late 90s when i thought of it the tech had allready been around for over 25 years prooving im not stupid and i DO understand Phisics. Thank you for clearing this up

[LCardoso]

James May Q&A, for me, ist in the top 5 best youtube programs ever.