Kitty Estrogen is a Noise inhibitor. Only female humans have it. That's why everyone/thing on the planet has Noise and women don't.
This answer contains spoilers… (view spoiler)[After arriving at the New World, the men caught the Noise germ from the air in the area, and eventually, so did all the animals. The women were immune, and after being driven mad, by the Noise, some men convinced themselves that "What was unknown was dangerous" because they could not tell what the women were thinking, the begin to murder them and anyone who tried to protect them. (hide spoiler)]