This isn't a system configuration problem @BernullyBites. It's a mapping one. I now suspect this might be a bot.
@Aladad
No, I don't think there's a way to disable the sound for env_spark. Worst you can do is overwrite the spark sound file with a silent sound, but then there won't be sparks sounds at all, anywhere in the game.
If you're making a custom mod, you can modify the entity's code to have a flag that disables its sound.