The cannabis plant when left to itself doesn't create much THC (which is what gets you high), but it is very useful for making rope and clothing, as well as oil and other products. Only when you make sure that you only have female plants (and take care of them in a certain way) do they produce lots of THC.
So just because the plant is growing somewhere doesn't mean that someone is smoking it.

I'm not deaf, but just in case you don't get an answer that stems from personal experience:
Your hearing loss in the one ear is (I'm assuming) caused by the ear canal being blocked. Your sensory organ still hears you chewing because the sound is transferred through the bones of your skull to your ear.
A deaf person has a different problem: their sensory organ is damaged or missing, so it doesn't matter where the sound comes from, they don't hear it.