Strange/creepy noise is playing around my sim for no reason

@ChahonovaThough I am not certain exactly what you are hearing I can offer a few ideas that may help.

Are you playing on PC/Mac or console?

If you are on PC/Mac do you have any mods or custom content?More about that in a moment.

First I suggest taking a look at your Audio settings under game options.

* Enable Mood Sting - Play audio every time the selected mood changes.

 - Untick this box to avoid this excess noises when Sims become focused, inspired, sad etc.

* Music - This controls the background music that plays on the main menu and while in CAS or build/buy mode.
You can hover over each option and make adjustments while playing to see if it helps.

Besides in Forgotten Hollow are there any particular areas where the sounds are more noticeable?
There are a lot of ambient / background noises to add more life to the game. Wind blowing, animal sounds, running water. traffic and in Forgotten Hollow bats squeaking.  Adjusting the Sound Effects volume may help.

Please comment if this helps solve your problem. 
If not there are other steps that can be taken.

Troubleshooting tips
https://answers.ea.com/t5/Technical-Issues-PC/READ-FIRST-Troubleshooting-your-Game/m-p/3621199

- EQ Avid Sims Player

Sorry for the delayed answer

Thank you fort your attention~

I play on PC.

The sound is not linked to the emotions or "background noises".

It sounds a bit like the sound that the Reaper has around him.

When the noise begins, if I pause the game, the noise continue till it ends (they a several "sort" of noises. They are during 1 to 4 seconds, depending on what "sort" of noise is played)

I have mods on, if you want to know

@Chahonova  Welcome back 🙂   Let's walk thru a few tests to further investigate the cause.

Two things caught my attention in your post.
*It sounds a bit like the sound that the Reaper has around him."

*...if I pause the game, the noise continue till it ends"
The best way to test is on a vanilla game without mods or custom  content.
Protect your current saves, mods and tray folder (contains creations not yet shared to the gallery).

Make a copy of each of these folders and save to desktop or somewhere safe.
When that is done remove (not disable) mods / cc and the localthumbcache.package must also be deleted. 

Test the game to see if the issues are still there.

If the sound is gone there may be an outdated mod that needs to be updated.

You will need to contact the mod creator for help with that.

That brings us back to the sound continuing after the game is paused. The cause could be in your PC itself.

If that is the case we can look at that once you do the above testing.

Troubleshooting tips
https://answers.ea.com/t5/Technical-Issues-PC/READ-FIRST-Troubleshooting-your-Game/m-p/3621199

Edit to add:

Do you have "Grim's Ghoulish Guitar" in your game? It creates a smoke cloud and the Grim Reaper sound when played.
The guitar is a promotional item made available as a bonus for signing you for the newsletter.
https://www.ea.com/games/the-sims/the-sims-4/news/GrimsGhoulishGuitar

Mods and or custom content are players choice and can make the game more interesting and fun for some players.
Unfortunately they can also cause unexpected problems.

Do you have Grim's Ghoulish Guitar (EA bonus for signing up for newsletters)  in your game? It makes a creepy noise like the one that follows the Grim Reaper.
Testing on a vanilla (no mods/cc) folder is the best way to investigate causes of issues.
Instructions are in the link below:
Troubleshooting tips
https://answers.ea.com/t5/Technical-Issues-PC/READ-FIRST-Troubleshooting-your-Game/m-p/3621199

Be sure to protect your saves and any items not shared on the gallery.
Make a copy of your saves, screenshots, tray and mods folders and save them to a safe place outside the game.
Once those files are safely stored out side of the Documents\Electronic Arts\The Sims 4 folder you will need to create a fresh folder for testing.
There are two ways to do this and I have successfully used both.
*Once you have a copy of the files above open The Sims 4 folder and delete everything. (My personal preferred method).
*Second method is to rename The Sims 4 folder to The Sims 4.old which will preserve all the contents.
*All the folders will be freshly generated when you open Origin and start a new game.
*Play for a bit in the new save to see if the odd sounds are still there.
If the sound is gone you may need to update any mods or cc you have in your game.
If the sound is still there without mods/cc there may be an issue with your PC such as outdated drivers etc.

Please let us know so we can continue to help you troubleshoot.