On Sat, 02 Sep 2006 14:25:05 -0400, "Roger (K8RI)"
wrote:

On Sat, 02 Sep 2006 18:22:41 +0100, wrote:

On Thu, 31 Aug 2006 21:19:11 -0400, Roger
wrote:

snip

I've been looking at headsets recently and came to the conclusion that
the QFR XCC clone is a good compromise at $240. Compared to other ANR
headsets it has some of the highest passive attenuation though only
~10db electronic. If the electronics fail it should still be very
good.

By the way Roger you mentioned in a previous post that 3db was
half/double. I think you're still thinking of power not volts.
I assume ANR refers to volts so think 6db = half/double, or am I
getting rusty with all this?

Sound (and our hearing) is logarithmic so I'm pretty sure that the 3
db holds for sound as it does for power.




David
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Roger, now you've got me thinking:-) As you say it's logarithmic but
if I'm not mistaken 10w to 100w =10dbw, 10v to 20v = 20dbv. I don't
know how ANR is measured so I'm guessing dba but it looks like double
= 6db. In an expample I found on the web and you compare say the Rifle
& Threshold of Pain there's 6db difference. That would suggest
headphones with say 26db passive attenuation would reduce the sound
level by a factor of 40. If you use 3db then it would be a factor well
over 500 which I think would be unrealistic.

Source of sound Sound pressure Sound pressure level
pascal dB re 20 µPa
=============================================
Rifle being fired at 1 m: 200 Pa = 140 dB
Threshold of pain: 100 Pa = 134 dB
Hearing damage during short term effect: 20 Pa = approx. 120 dB
Jet, 100 m distant: 6 – 200 Pa = 110 – 140 dB
Jack hammer, 1 m distant / discotheque: 2 Pa approx. 100 dB
Hearing damage during long-term effect: 6×10-1 Pa = approx. 90 dB

David (GM3RFA)