Headphones.

[zabado]

How do "noise cancelling" headphones work. Is there a big difference to normal headphones that warrant the extra cost ?. Thanks.

[ToraToraTora]

They listen to the ambient noise and generate am equal and opposite sound. Essentially a peak where there is a trough and vice versa.

[Old_Geezer]

Always marvelled at how fast that has to be, to analyse the incoming and create/produce it's negative waveform while the original sound simply travels the width of the headphone at the speed of sound.

[Old_Geezer]

Whether it warrants the extra cost is a matter of subjective judgement.

[retrocop]

I haven't a clue how they work but TTT has already explained. I can vouch however that it is worth paying the extra cost for noise cancelling cans.
I shoot high velocity munitions and have for many years used ordinary cans with bits of 4X2 stuffed inside. I now am quite deaf . I have used ,too late, noise cancelling cans and they eliminate the sharp crack from a gunshot which is quite injurious. Trouble is the two AAA batteries have to be exchanged every month as they die very quickly after a day on the ranges. Well worth buying them. I use Peltor and they would have saved my hearing if I used them 60 years ago.

[ToraToraTora]

OG: "travels the width of the headphone at the speed of sound." - err no it's travels at the speed of light! The sound is the speed of sound until it enters the electronics then it's the speed of light (or there abouts).

[Old_Geezer]

As I see it, under normal circumstances ambient sound travels at the speed of sound to your ear. If it couldn't get through the earphone insulation at the speed of sound you wouldn't need to try and cancel it.

[Hymie]

In their simplest form, noise cancelling headphones will simply employ a microphone in each ear piece (configured to pick-up external noise) and add that signal (in anti-phase) to the audio signal being listened to, in instantaneous analogue form. More expensive models may use digital processing, these days real-time instantaneous audio signal processing is cheap to do.

I have a cheap pair somewhere, lost in household junk, which included manual adjustment of the noise cancelling effect, to optimise the performance for a given situation.

[mjwman]

I have Sony MX1000M3 phones. I treated myself. (£270).
One of my best purchases ever. Sound is brilliant and and I can listen without hearing the telly or wife jabbering on.
They are particularly good when travelling and especially on a plane as everything is suppressed and I can just get on with my films!