Infant/Toddler has no sound

My main sim family has a toddler who makes zero noises. They make the motions of talking/babbling, but there is no sound. This also happened when they were infants. I have checked other households, and all the other infants/toddlers have sound, just not her. Even in CAS, there is no sound, unless I age her up and then back down, but the moment I reenter the game, she loses all sound again.