December 2018
Could it be your headphones aren't working like intended or the cable is fully plugged in to your device?
January 2019
Does it also happen when you're not wearing headphones? I have a occasional sound glitch too, and I'm guessing it's just a bug.
February 2019
If it is a bug, please make a new post in the bug forum about it.
You can find the bug forum over here: https://answers.ea.com/t5/Bug-Reports/bd-p/the-sims-mobile-bug-reports-en
The bug forum has a small list with questions which might just help solving the problem!
In this case a video of where you can hear the sound would be helpful.