Do they have batteries? Or do I have to charge them?
USB charger but the battery life is long (my NC700 pair last 17hrs I think)
Do I simply turn them on and then they cancel all noise for as long as they are on, even if I am not listening to music (which I cannot)?
Yes they work even when not listening to music, but the term 'noise
cancelling' is a bit misleading because it gives the impression that they get rid of
all sound, but they dont. They were developed originally for cockpit headphones for pilots & at cancelling *continuous* lower frequency sounds like lawn mowers, they border on miraculous. But for higher fre & more intermittent sound - like voices for example - they are less successful.
This is in part because they have to pick up the sound & send the alternate 'cancelling' sound, & often there simply isnt time.
That said, all the NC headphones have come on in leaps & bounds in recent years & are better at mid range & higher frequency sound amelioration.
PErsonally I have found the Bose to be the best, most effective & comfortable but its a very personal thing.
They do do different ones though. The in-ear ones are never as good at blocking out simply because they dont have the same level of passive cancellation. I use the over-ear ones with ear plugs as well.
They do make different ones, and it's been my experience that you get what you pay for. I have some QC
ULTRA in-ear buds (i bolded the ultra word because there are QC & QC ultra ones & the ultra cancel way more sound in my experience), which i use if i need to cancel neighbours hot tub humming sound through the summer with the window open, as they more comfy to sleep in (i find ear plugs useless for that sound as it's too low).
And NC700s over-ear kind.
They unexpected joy of them now i finally got a smart phone is that I can block out most background sound & still make a phone call (they connect to phone via bluetooth so can use their mic & hear the call through the headphones)
In terms of sensitivity I have not experienced any issues with having a 'device' near my head - I cant tell. Having said that, now I think of it, some yrs ago i bought their wired in-ear ones (very old model) & they did make me feel nauseated so i had to send them back.
Sadly I am unable to go to a store and try a pair, and they are expensive.
If you buy direct from Bose there is a 90day money back satisfaction guarantee - which I have tested, twice (1st as mentioned above & 2nd time when i bought their original quiet comfort ones but found them to be no better than than my NC700s).
So you can buy them use them for several wks & as long as you send them back within the 90days, you will get a full refund regardless of the reason - ie they dont need to have a fault you can just say you didnt like them.