You got damage from a fan app? I used to use fan apps with headphones on when I needed to concentrate at work. Also slept with one of those Dohm white noise machines.
I went through it really sloppy as I hate listening to those tones. But the volume seems slighty softer around 4,446 Hz. Hmmmm...
And now my ringing is angry with me.
I don't understand hearing aids either. Don't they just increase the volume on certain frequencies? So you've got an amplified 6 kHz wavelength smashing through all of your 18-7 kHz (or whatever) stereocilia?