Read book on neurophysiology of music (yes, another one). Realized for the first time - as in actually realized, not just idly mathematically computing it but really understanding what it meant - that I can hear less than 10% of what most people can*. This was a jolt, to make a massive understatment.  I spent an entire train ride re-looking up numbers and doing addition and multiplication to make sure my arithmetic was not somehow wrong.

*frequency-wise. Thankfully, perception is on a log scale. So it's not so bad. Somewhere between 20%-50% depending on how you count, if you go on the log scale.

The human hearing range is approximately 20-20,000 Hz. Mine is something like 20-2,000 Hz. Kinda.

I've looked at this picture before and never really cared. I have looked at the piano keyboard before and cared a lot that...

• around 1 octave above middle C things start getting softer
• 1.5 octaves above middle C they're soft enough I have to concentrate to hear them
• by the time you reach 2.5 octaves above middle C, I can no longer distinguish between pitches
• around 3 octaves above middle C, I can't hear anything except the clicking of a key being pressed down

These are things I've known for years while playing music. Things I've had to work around, things that caused terror when playing high right-hand runs in competition pieces. It never really occurred to me to connect the two before (I don't know why), but they match up. Terrifyingly well.

• around 1 octave above middle C = around 520 Hz, which is the same point where my audiogram starts declining
• 1.5 octaves above middle C = 740 Hz, where it crosses the halfway mark (as in "most people percieve sounds at this frequency twice as loudly as I do")
• 2.5 octaves above middle C = 1400Hz, and it's worth noting that between 6,000-20,000 Hz is the "I hear a really high sound, but can't distinguish pitch" range for most normal-hearing people.
• around 3 octaves above middle C = 2000 Hz, about where I start bottoming out (for all reasonable intents and purposes, if your audiogram goes down there, you're essentially deaf in those frequencies).

I'm not sure why this makes me scared, but it does. Were I much more panicky, I might be running around screaming "Aaaah! AAAH! My ears are broken!!!" but... I'm more just stunned and shaken. Which makes no sense, because I've known since I was 4 (and grown-ups told me) that... well, of course I don't hear stuff. Duh. But this seems like... the value of \$stuff is far - orders of magnitude - higher than I'd thought. For 17 years.

This may explain some of the looks I've gotten from audiologists. And the conversation one of my teachers had with me after meeting my audiologist for the first time (in an IEP meeting the previous night I hadn't been allowed to go to). It went something like this:

Teacher (very, very paraphrased): I met your audiologist last night and they explained your hearing loss to me and we listened to a tape of what you hear...

Me: There's a tape of what I hear? Cool! Can I listen to it?

Teacher: ...and I was amazed at how... I mean, you handle... when I first met you I couldn't tell... How do you...

Me (confused): Well, this sounds normal for me, I don't really... handle it, it's...

Teacher: Anyway, I just - it's amazing.

Me (very confused): Thank you?

Bell: *ring*

Two pieces of my world have just exploded into context with each other. I'm scared. And excited. And very, very curious. And terrified.

TRAIPSING ACROSS MINEFIELDS HERE I COME