The thing that appears to Sam isn't the Voice. If it were to be compared to any one thing, spirit may be most accurate.
"She isn't listening."
It sounds like a chorus of children's whispers, like leaves shaking in a breeze. "She doesn't care." It sounds petulant and put-upon, though it brightens considerably. "You care, don't you, Sam? You care so much. Do you care about us?"