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What are we hearing below 20hz?

It is often said that the human ear can hear 20hz to 20khz in range. This varies from one person to another and usually diminishes as we get older. So..........I listened to a test record the other day. It had tones from 20 hz down to 15 hz if I remember right. Anyway, at 20 hz, I could hear it very well. Each note after was down in 1 hz steps. I could hear down to 17 but each below 20 became more faint. This would be due in part to the speakers which are rated down to 18 hz. If I cannot hear below 20 hz, what am I hearing?

Likewise, a pipe organ can reach 8 hz from a 64 foot pipe. Few of these even exist but they do exist. 16 hz is produced from a 32 foot pipe. Most pipe organs probably don't have much more than the 32 foot pipes and some don't even have that. At any rate, the sounds are clearly heard, at least something is heard. The latest pianos are now producing 16 hz tones. We are able to hear the notes. If we can't hear below 20 hz, what are we hearing? 

billpete
quincy
400 posts
 

Interesting post!  Thanks for the question and replies!  I found it interesting and educational!

billpete OP
268 posts
 

So, has anyone ever heard or felt the presence of the 64 foot organ pipe? I have not but would like to. Hard to imagine when the organist hits that note, that the crowd hears nothing. That would be very odd. Anyone??????????

Also something that floats around the internet is that 14hz is a lethal tone. A ridiculous claim. The tone at a certain SPL, certainly could be lethal as could many other frequency range tones. It is the SPL decibel level that is the danger. Nobody dies in church with a large pipe organ. The lowest tones can make you feel a bit uneasy, kind of like a carnival ride. I enjoy that odd feeling that I get from the deepest bass notes. It borders on "uncomfortable" like a thrill ride. 

Thanks

roxy54's avatar
roxy54
8,203 posts
 

I once owned TDL Monitors that were large transmission lines and were said to reach down to 17hz. On a few recordings I could feel what seemed like a mild earthquake in the room.  

billpete OP
268 posts
 

@roxy54 

Yes, my AR 9's cause considerable vibration in my listening room as well. The hardwood floor vibrates at times, interesting sensation. What did you hear at the same time? I hear very low bass, according to the test record, I was hearing 17 hz. Probablly most bass below 30 hz is going to cause considerable vibration and will also depend on the SPL as to how much. I'm still trying to figure out what we actually hear at those lowest tones but from what I've read, it is humanly possible to hear 12 hz. Still poses the above question. What happens at 8 hz or 10 hz? 

edsemble
2 posts
 

We can discern distinct pitch @ 20 Hz, some tests reporting 17-18 Hz.

We can definitely hear sound of some sort below 18 Hz, but we wont hear it as a tone. When I played back 16 Hz on the subwoofer, I heard a chuffing sound, like that from blades of a helicopter sitting at idle. But no sense of a distinct tone.

Playing my record of Holst The Planets - Saturn, ~ 2/3ds into it, I could easily hear the organ pedal tone of E(0) 20.6 Hz - as a distinct tone.

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