Comments on Profile Post by Serious

How'd you measure, GSR, EMG, or similar? I'm thinking you're going for physiological responses since you mentioned it being subconscious. Could also just be cell-level response to the HF vibrations since iirc ears just aren't wired to sense that high up, though I'm not 100% sure how the hair cells in ear respond to signals that high? Would be interested in a new thread on the topic!

Also, this means that massive spike at around 42kHz (your measurements was it?) in the HD800 might actually affect our perception, BWAHAHA.

I used to hear active ultrasonic alarm systems in my youth. Had to leave a jewelry store once because of it.

It goes away with age.

So basically I thought I couldn't really hear past 18.5 - 19.5kHz (it varies day by day) since that's where it gets very quiet during regular sweeps. But last weekend I was somewhere where they had set up speakers to scare away birds that I (and other young people) could hear. I pull up the spectrum analyzer on my phone and it reads at 20.0kHz...

So this made me realize that I could hear 20kHz if it's at a very high level. I also remember reading that the threshold just drops way off around 20kHz, but doesn't reach 0 and some people actually responded to 28kHz at 100db+:
https://asa.scitation.org/doi/pdf/10.1121/1.2761883
Someone also claimed that you could give people headaches by playing a very loud 40kHz tone.

Well, so I did a blind test in foobar between digital silence and a 30kHz tone at what should've been around 80db playing on my speakers at the other end of the room...
I could hear the difference and stopped at 10/10. It's not like a high frequency whine, it's more like a hissing sound that gives me headaches though.

I also tried 60kHz (since the speakers should still have some output there) and it was more difficult, but I still ended up getting a 10/10.
Maybe there are subharmonics somewhere or just a general rise of the noise, though. I think it'd have to be less than 60-70db down for it to not be masked by ambient noise. It was pretty quiet last night when I did the test.

@Lyer25 Well, that is if music calls for it and I think even music at high sample rates doesn't have a ton of information past 20kHz because the mics with a good enough SNR for recordings just don't go as high.
Vinyl rarely has much information past 20kHz and phono carts definitely go past 20kHz

@Syzygy Could you hear it like a CRT TV or was it higher up? Some elevator doors I know also make a high pitched sound.

Thinking subharmonics might explain the situation too (if I understand the concept of subharmonics accurately haha). That said the results are interesting and it may warrant investigation in a more controlled setting.

I don't think it'd likely be perceived as a hissing sound, something that high up. Could be any of a number of factors, I know jack shit about the anatomy of audio gear compared to like 90% of the people here so can't for the life of me guess at the cause, but sounds like the transducer might be straining somewhat? That, or the sheer SPL is causing the hair cells in your inner ear to vibrate.

I was on a pre-med track before I shifted to psych but I was pretty crap at it IMO, so my understanding of how hair cells work might be off but isn't it that the structure of the cochlea makes it so that specific areas respond to a narrow range of frequencies and it's because the distal end of the spiral, which senses higher frequencies, is what's closest to the pinna that HF hearing often goes first?

Either way, could be that reflections generated in the environment or whatever are agitating the hair cells and hitting their resonant frequencies, causing that hissing sound.

And before I forget, that thing about the 40+kHz spike in the HD800 affecting perception was mostly humour. I'm aware that recordings don't go that high, haha. Whether or not resonances from waves inside the enclosure might generate harmonics that high up though.... Lol.

Well, I wrote hissing sound mainly to say that I didn't hear a pitch. Pitch differentiation stops around 18kHz or so for me, where my hearing threshold gets a lot higher. Past that it all sounded pretty much the same to me.

I'm sure the tympanic membrane doesn't simply stop vibrating past 20kHz (response is probably more like that of a microphone), so I guess it's possible that I was mainly hearing some noise generated by our inner ear that corresponds to pressure changes or so. Not sure, I really don't know as much about the ear as I should.

I might do a more thorough test tonight including measurements to see if there are subharmonics generated or if the noise floor rises enough to be audible above ambient noise from playing ultrasound. I have a feeling I'll be hitting SNR limits with the mics I have here, though.
Maybe I'll even make a thread, this is getting way too long for a profile post.

>I really don't know as much about the ear as I should.

Likewise, haha. In my case my hearing stops just around 17.5kHz I think, or whatever that mosquito tone at audiocheck is. Past that I "feel" sounds, but it's more a sense of pressure than hissing. Could just be my ears are in worse shape, and there's the tinnitus besides.

This is definitely getting to be overmuch for a profile post, but a thread might warrant more substantive evidence. This is where the measurement gear comes in handy I guess :))

I could definitely hear the alarms. Some poorly-made dog whistles, too. Other times I would "perceive" something, and knew it to be related to hearing, though it's hard to call it hearing since it was so far outside the normal range.

And yes, CRTs were always annoying, and similar to the ultrasonic alarms.

As for measuring your ability to hear it, I don't think typical audio speakers are a good choice, since they're not really designed to faithfully reproduce those frequencies. You'll need a specialized high frequency transducer to ensure that it's not emitting harmonic noise you're perceiving instead of the frequency under test.

Yep, especially since I just used my Voxativs. There are cheap plasma tweeters on eBay that I'm sure will have the bandwidth required, but I don't think they're low distortion.