Macbook Pro Fan noise question

This is completely normal. The MacBook may be running internal processes or simply may be getting warm and will regularly run the fan to keep the internal components from getting abnormally hot.

If you close all your applications, however, and put it in a very low usage state (CPU wise), does the fan stop? If not, there may be something wrong internally that makes the computer think it's warmer than it is, thus prompting the fan to run.

The fan of any macbook will always run no matter what. Macbooks have no fanless mode or anything else. From startup to shut down your machine's fan will always run at roughly 2000rmp on idle and the fans can ramp up to 6000 rpm under full load (you can see this with a monitoring program like iStat or HWmonitor) to move fresh cool air in and hot air out.

The fact that you only hear them when you are in a silent room shows just how quiet macbooks are.

If your macbook fans don't spin up the internal components of the macbook would overheat after a while especially while under load.

TL;DR. totally normal behaviour, don't worry about it

What you can do is install a temperature/fan speed application and see what the results are. As GhonaZ indicated, the fans are always in operation when the MBP is turned on and the default speed is 2k rpm.

If that turns out to be the case, run an Apple Hardware Test to see if it identifies a problem with the fan motor:

https://support.apple.com/en-us/HT201257

Note that an error free AHT is not definitive.

If no errors are detected, you can then go to sleep and close both eyes. 🙂

Ciao.

Running an Apple Hardware Test might still be a good idea.

Ciao.