Everybody's house smells in some way.
You almost never even notice the way your own place smells. You notice the way everyone else's place smells as soon as you walk in. There are their cats, and the soap, and the new furniture they just got. And those all add up to the way their house smells,
But you can only smell your own house after you've been away for a while—like, a long while. Not just a workday, but like a week.
It has to do with sensory adaptation (感觉适应). That's the scientific way to say that you just get used to it. And it's more pronounced for our sense of smell than for any other sense, like our hearing, for example.
Researcher Pamela Dalton at the Monell Chemical Senses Center has done a lot of work on sensory adaptation. She and her learn say that adaptation means you respond less when a stimulus(刺激物) is repeated. So when you are at home, the smell of your house is all around you. It never goes away. It's not just repeated—you're swimming in it. So you become adapted to the way it smells.
The thing with smell, though, is that you adapt to smells really quickly. After "even a few breaths" of a smell, Dalton says, you begin to acclimate to it.
You start to experience dial as being less strong and finally take no note of it at all. That's why you can smell your friend's house when you walk in, but you don't really notice it all the time you're there.
Being able to detect (探测) smells is important. It might warn you of danger, like an approaching tiger or something gone bad in your drinks. Or it might mean something pleasant, like fresh bread or blooming flowers.
Your nose can stay on the lookout for new smells that are dangerous or delicious. It might be a simple housekeeping thing, like a dishwasher in the kitchen or a towel in the bathroom that needs to be cleaned.
Then, if you still want to change the way your house smells, many things might do the trick, like candles, fresh fruits, or a bottle of perfume（香水）.
