This is a most excellent place for technology news and articles.
The sound produced by ANC is the exact 180 degree inverse (or as near as possible) of the incoming bad noise.
It's produced in realtime by dedicated signal processors and requires mic arrays feeding in the sound. The quicker your processing pipeline the better the match is and the more powerful the effect is.
There's no prerecorded sound that would work.
I've always wondered, does the ear experience additional, unheard "loudness" when using ANC?
Yes. On older generation/cheaper ANC this is perceived as increased "pressure". It doesn't seem louder but the physical sensation of loudness is there.
That actually explains the sensation I have with headphones provided by my work, I want to like them but the sensation is kind of unpleasant
The A in ANC stands for Active. It is actively listening to ambient noise in your environment to cancel it out with a waveform tailored to do so in real time. If the noise in your environment is very static (like a hum or whirring) it might be possible to embed a cancelling sound in the audio file. But it's likely it still won't line up properly to really cancel it. It's more likely to cause a worse sound because of being out of phase (like two leaf blowers going at the same time).
I hope that makes sense.
Do you want to just block all sound or do you want the extra features that come with active noise cancellation headphones like speech passthrough? What you are proposing doesn't exist because it makes no sense, active noise cancellation is done by recording the audio outside the headphone, inverting the amplitude and attempting to align the phase to cancel it out in real time.
In reality active noise cancellation only works for more or less constant sounds below 1000Hz, anything higher than that and the headphones block exactly as much noise as any other pair of sealed headphones.
You will get better noise reduction with IEMs than headphones, deep insertion headphones like Etymotic beat the pants off Bose for noise isolation at every frequency, are cheaper, and as a plus sound better than any noise cancelling set you can buy.
You need the live background noise to produce an inverted sound wave which will cancel it out. You don't have that in a piece of data or software.
There have been a lot of ANC responses focusing on the A (active) part. There are two parts to nose cancellation: active and passive. I agree ANC are sweet and all... The other comments have that covered.
If you're interested in exploring a potentially low cost alternative to expensive ANR headphones or earbuds... Know that there are two parts to noise cancelling: active and passive. Passive nose cancelling is how much the headphones or earbuds reduce the outside noise before the active part needs to step in.
SO, an option I haven't seen discussed yet would be to get some standard low cost earbuds and get some over-ear ear muffs to put around them.
Edit: literacy is for everyone... I didn't see the bit about using this for sleep. Over ear muffs plus earbuds wouldn't be very comfortable. Another option might be just finding some noise sounds you prefer over the nose you like. There are different standard noises... White noise, pink noise, brown noise... These might help make the frequency of unwanted sound your looking to block. This is a link related to noise colors after a quick search: https://www.hatch.co/blog/exploring-color-noises-for-better-sleep-with-hatch
Along these lines though when I did a lot of wood cutting I would buy the foam ear plugs, cut them shorter then use a hole punch to create a centre through hole that fit my earbuds. Replacing the stock rubber/silicon pads.
I would then compress the ear plugs with my fingers like you normally would and slip the earbuds in.
I would guess the earplugs efficacy was slightly reduced but it let me listen to music and podcasts while slinging a chainsaw for hours at a time without having to have ear damaging sound levels. I always used a helmet and earmuffs over the top for extra isolation.
Great ANC is still a premium feature that you'll pay a premium price for. But good ANC has made its way into the budget space and if you're willing to compromise on some features, you'll find some decent options. I usually pay attention to rtings reviews: https://www.rtings.com/headphones/reviews/best/noise-cancelling-earbuds
Afaik you have to replicate the same wave but in opposite "direction" (up/down sinus) to cancel out incoming sound so any anc earbuds have to have microphones and are dynamically shaping the sound.
You're asking for twice as much noise into your ears?
I'm certain there are recordings of background noise, but none of it will do what you're asking. It'd be like trying to cancel a recording of your voice by talking over it. A fun experiment to get the grandkids to do when they go home. Better yet, on the car ride home.
If you're okay with earbuds, Pine64's PineBuds purportedly have ANC
You're putting the cart before the horse. Tell us the specific situational problem that you're trying to solve. Like what ultimate end result are you trying to achieve.
That way we can help you achieve what you're actually trying to achieve
I've had a couple of good experiences with budget ANC buds, I used scarbir.com for his budget reviews, especially like that he assesses their phone call quality.
