If it's just in the game, try lowering the graphics settings to see if it helps. It may be that the computer is having a hard time keeping up with what's going on in-game. Lowering the graphics may help with that.
Here are a couple of threads on fixing issues with the Sound in Sims 4.
{SOLUTION} Sims4 No Sound Bug on Computer/Laptop
https://answers.ea.com/t5/Technical-Issues-PC/SOLUTION-Sims4-No-Sound-Bug-on-Computer-Laptop/td-p/6028762No Sound in SIMS 4
https://answers.ea.com/t5/Technical-Issues-PC/No-Sound-in-SIMS-4/td-p/3470839The suggested fix to having to repair game before playing is to reset the Sims 4 folder.
To Reset the Sims 4 Folder:
Move the Sims 4 folder from Documents to the desktop. Launch the game again so it creates a new Sims 4 folder.
Try a test-game to see if things are working okay. If so, start copying over the folders and files listed below:
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Options.ini File -- The graphic/sounds/gameplay options
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Saves -- Saved game files - leave out slot_00000001.save which is the autosave. It is not used anymore.
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Tray -- Sims, Houses, Rooms and Community lots
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Screenshots -- Photos you've taken with the C key in-game.
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Recorded Videos -- Video clips you've taken with the V key in-game.
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Mods -- Game mods and Custom content like clothing, hair, skins, and makeup
** Put mods back one by one to make sure they all still work.
Again, please do test your mods and custom content as they can become outdated with most new game patches.
How to Fix Problems with Mods/CC
http://www.carls-sims-4-guide.com/forum/index.php?topic=25031.msg426156#msg426156If the above doesn't help, please ask about these issues over at Sims 4 tech forum at AHQ -
https://answers.ea.com/t5/Technical-Issues-PC/bd-p/The-Sims-4