Bates Motel. Twelve Rooms, Twelve Vacancies.
The OP says he is disabled & spends a lot of time in the apt alone. I’m really reaching, I know, but is it possible that he uses a motorized wheelchair that makes a lot of electric engine noise?
If this was the case, maybe if the OP had 1-2 spare electric chairs & sent them off in different directions while he went about his business, he could throw her off?
Or, if she was still following him, maybe he could buy a dozen roombas? He could turn them on and drop them like chaff as needed as he went about the apartment.
But then, how would the OP know that she hasn’t just dropped a sound-activated & sound-homing roomba of her own to chase him around all day while she’s at work?
“Dear Heartless Bitches International. I never thought I’d be writing to you, but I have found an easy victim and have discovered the perfect way to drive him Absolutely Crazy…!”
Addressing the OP and nothing else:
You know, there are certain times of day when people take showers, and there are certain times of day when people eat and cook meals. Isn’t it possible that her schedule just happens to match your own?
Count Blucher is right, what you need are heightened counter-detection measures. Perhaps a radio in each room, each tuned to a different station (or static). Cover all surfaces of your apartment with sound-dampening material. Replace the ring tone on your phone with a flashing light, and use headphones for the computer/TV. Absolute stealth is the word. That’ll teach her.
Make a recording of yourself reading a passage from a book. Using multiple playback devices and the “repeat” function, ensure that your voice can be heard in all rooms at all times.
This will confuse her and may screw up her eavesdropping.
It won’t make any difference when it comes to the cameras she’s installed in all the light fixtures.
It’s a weird problem but I have to go with the radios. They don’t have to be loud, but just loud enough so you don’t think the upstairs neighbor is following you around.
what he needs to do is cover everything (ya, including the ceiling) with flour, setup a 24 hour motion detector camera and call the ex-parapsychologists.
… twelve showers.
Its awful quiet. Has the OP heard anything yet?
“It’s just apartment house rules
So all you 'partment fools
Remember : one man’s ceiling
is another man’s floor”
posskb, how do you think she KNOWS where you are at any moment in your apartment? Just curious? How could she possibly hear you below? (Just bear with me, folks)
Maybe she worries about you.
Loud bagpipe music – that oughta screw her up for awhile.
LOLs at the mental image of a powerchair with roomba chaffpacks!
Gee, you rarely hear a reference to “pork” from someone named Cicero.
I had never heard of Cicero Pig. I am not entirely pleased. 
Now I keep thinking of “Deliverence”.
He’s not coming back in here, is he…sigh.
Maybe the OP doesn’t realize that it’s him that’s actually the one who is following her around listening to her. Hmmmm?
Dammit, we’ve lost another one to the Bungo Straights. From now on, Area no. 7 is Off Limits…
False Telephone conversations.
Not “I’m pretending to be a drug dealer/criminal” calls, or you’ll have the cops all over you.
Nope.
Pretend to be in the CIA, involved in hair raising operations inside the US.
But only very infrequently, when you know she’s listening, you just want to mess with her mind, AND you have something of a script worked out.
“Good morning sir. Yes sir, the operation went well. We killed three terrorists over in (crappy neighborhood) who were getting guns from (gang name). We also took out three gang members. No sir, one of them got away. We think it was Muhammed Muhammed. But we have a lead on him. No sir, I can guarantee that it won’t be on the news. We cleaned up the scene and destroyed the bodies. Yes sir, I know how sensitive this is, nothing can get out. Yes sir, thank you sir. I’ll report back when we know where to find this scumbag.”
Watch the look on her face next time she sees you.