What happens to the human ear as it naturally goes deaf?
Hearing loss is caused by different things, but your probably thinking of age-related hearing loss.

When people go deaf, it is be because "hair cells" in the ear break.

This breakage results from overly loud frequencies, or just random damage to cells over a lifetime.

If your last remaining hair cell that is tuned to a certain frequency after all the other ones have died gets killed somehow, it will depolarize and send an action potential to your brain telling it to hear that sound.

But that would be a very faint sound, since only one or a couple hair cells die off.

But in reality, it usually isn't that you hear a sound for the last time before going deaf, you have a faulty premise hear!

it's NOT like the ubiquitous "seeing the light" that happens when your heart stops.