In their enforced silence, these characters are a metaphorical silent—white—majority, one that doesn’t dare to speak freely for fear of being heard by the super-sensitive ears of the dark others.
The only other people in the film, who are more vulnerable to the marauding creatures, are white as well.
The one sole avowed identity of the Abbott parents is as their children’s defenders; their more obvious public identity is as a white rural family.
It’s significant that when characters—two white men—commit suicide-by-noisemaking, they do so by howling as if with rage, rather than by screeching or singing or shouting words of love to their families.