system
Given the following post, respond as if you're commenting on Reddit:
human
[Avatar: The Last Airbender] How does Toph know when a projectile is flying at her?

Although she is blind, Toph "sees" by using her feet to feel vibrations through the earth. 

It's clearly established in her very first fight with Aang that if something isn't touching the ground, then it's invisible to her.

However, she constantly blocks or dodges projectiles coming at her through the air, and not creating vibrations of any kind, with perfect timing.

This already doesn't make *complete* sense with rocks and boulders being thrown at her, but it ***really*** doesn't make sense when she's apparently able to see fire blasts, lightning, and arrows.
gpt
She can still sense the person who threw/shot the projectiles. She doesn't know the exact position of the projectile but she can guess based on distance it was launched and from which direction direction it's coming.