It's all relative, that is, your hearing and brain will adjust to how much ambient noise there is. Up to a point anyway, people go a bit mad if there's too much ambient noise (hence the article).
Likewise when ambient noise goes away though. There's a challenge in a sound studio somewhere that blocks out pretty much all sound, challenge being how long you can last in complete silence. Supposedly you can hear your own blood flowing in there.
It's also why people experience noise cancelling headphones as applying a 'pressure' when they first put them on; there is no pressure as such, but just the sudden absence of ambient noise their ears/brains are used to.
Likewise when ambient noise goes away though. There's a challenge in a sound studio somewhere that blocks out pretty much all sound, challenge being how long you can last in complete silence. Supposedly you can hear your own blood flowing in there.
It's also why people experience noise cancelling headphones as applying a 'pressure' when they first put them on; there is no pressure as such, but just the sudden absence of ambient noise their ears/brains are used to.