That is logical.
Hear and understand, yes. Because that would be preliminary for the command. If the geass cannot be understood or heard then it's nulled, rendering them immune.
So yes, animals of any kind are immune as well, since they don't
understand human language(s).
Maybe the preliminary changes for animals, instead the 'tone' of the command? No, that doesn't make sense.
So it only effects people. Machines are most likely immune as well, and so it is more like Lelouch's geass afterall. The simple fundamental of the geass is different.
Ironically, Mao is rendered immune to both Lelouch and Rai.
Mao > Wears heavily tinted sunglasses and headphones.
Lelouch: Requires optical to issue command successfully.
Rai: Requires hearing-understanding to issue command successfully.
Maybe Eternal Dreamer could enlighten us on some of the Mao dialogue between him and Rai. Since I've been stucked on an entirely different route doing an entirely different scene.
