On Sat, 02 Sep 2006 20:50:46 +0100, wrote:

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

That is correct, but sound is analogous to power not volts.


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

When I had a two blade prop on the Deb is was measured at 93 db at a
distance of one city block and full RPM. So you can see why the
neighbors off the end of 18 complained when I'd go over at roughly 300
feet on climb out at full power. :-))

David (GM3RFA)
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com