About Invulnerability

[Sage]

Given that Kaden was saying the bones would become so dense they couldn't move, and not 'so massive that they'd block the ear canal,' he's still right. If something is so impossibly dense it cannot be moved (and in this case it doesn't even have to be that heavy; they're sound waves), then it... won't move.

Neutron stars are absurdly dense, and they're relatively tiny.

Basically, he's just going to make the ear bones so heavy they won't budge under the 'force' of the sound wave.