An idea for the humans/earth is space Australia. These aliens fight with their voice. But our songs are stronger. Opera singers? They can't even fathom, they just faint. Thought you'd have fun with it! Thank you -- Anon Guest
The Karolai had thought they were masters of tactics and the ultimate weapon. None had dared oppose them for a thousand years of glory. Their empire spanned most of a galactic arm, and they kept tight control of it with sonic weaponry. Like all empires of might makes right, they made one fatal mistake:
They tried it on the Humans.
Sound has been used offensively by Humanity on many occasions. As crowd control, as attempted bowel control, and as crime prevention.. Sound has been used benevolently for just as many purposes. Humans know about sound. They have even damaged themselves with its use over the centuries.