Nothing. It's normal. It means you have to use the restroom or your food is digesting
When they don't feel like making noise and at night.
you cant. the sound is probably either a disk spinning, or the fan running so the machine doesnt melt. if its not making noise, its probably off or broken.
make sure your computer is unplugged and remove the fan from inside, and thoroughly clean it. this will "lessen" or remove the windy noise.
WD40 applied at appropriate places.
Lubricate.
The only reason your mac would make noise is if it is cleaning its self. If you first get a mac it might clean its-self more often. Once the mac is comfortable in its new home it will stop making the noise. I work at the apple store, and I can a sure you that your computer is fine. Remember to stay calm because all macs do make the sound, it is completely normal, and your mac will eventually stop making the noise, once it is use to it place.
Your chirping smoke alarm is making noise because it is indicating a low battery or a malfunction. To stop the noise, you can replace the battery or reset the alarm according to the manufacturer's instructions.
making
Going to the garage to get new brakes before you gear box goes
Your toilet may be making noise every few minutes due to a faulty flapper valve, a leak in the fill valve, or a problem with the water level in the tank. These issues can cause the toilet to constantly refill and make noise. It is recommended to check and repair these parts to stop the noise.
Unplug it.
Bleeding the air from them usually helps.