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  3. 161038-109487

I think I over treated my room. I can't hear anything.

Now that I got your attention. I've been posting questions about treating my listening room in my new house that I'm moving into in a month. 
I just remembered a trip I took to the Johns Manville testing facility in Littleton, CO back in 2002 while working for an Insulation company here in Milwaukee. Allied Insulation.
A small group of us walked into this room and it was hard to hear anyone talking when standing next to one another. I couldn't find any info about that facility but I did find a site where the room looks the same.
Most of you know if you use a SPL meter in any room in your house with nothing running the meter still registers 30 or so decibels. This room claims to have a minus 9 something. They also claim that 45 minutes is the most that anyone can handle. Check this out.
https://www.smithsonianmag.com/smart-news/earths-quietest-place-will-drive-you-crazy-in-45-minutes-1...
golden210
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oldhvymec
5,101 posts
 
How do you get to -9, really that's interesting.. That's less than what we can hear? I don't understand. It's a negative sound pressure. How does that work? Got me on that one.

Regards
pokey77
1,259 posts
 
@noromance

I definitely here on that second part.
toddalin's avatar
toddalin
145 posts
 
Yes, -9 dB is way less than we can hear, but it is a valid number.

Zero dB is defined as 20 micropascals ( 0.00002 pascals), so any sonic energy level less than 20 micropascals is a negative dB level.
jc4659
512 posts
 
Makes you wonder if you can hear noise such as that from a vibrating transformer in any equipment that you would otherwise swear is dead silent.  How about the rumble of a turntable or the stylus tracking grooves on a record with no audio connections except power?  This would all be noise that is typically drowned out by ambient noise.  I bet cooling fans would be really noisy.

wolf_garcia
6,592 posts
 
I have a small jet and not only is it hard to keep vinyl records under control on it (especially on take off and landing), it gets really hard to focus on micro-nuance during a flight due to the ambient roar of the engines...if I can get my pilot to just glide a little it's so frightening for the passengers it's really not worth it. Acoustic shows on a DC3 used to be the same issue as my quiet ukulele solos were basically inaudible...got paid anyway.
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