>FROM A PREVIOUS EPISODE OF "AS THE DB TURNS"
But in the end it doesn't matter, does it? A dB is a dB. An increase in
SPL
of 6 dB is the same as an increase in sound power of 6 dB. Just like a
6dB
change in voltage results in a 6dB change in power. Wonderful things,
th
drcuthbert [mailto:drcuthb...@micron.com]
Sent: Thursday, January 23, 2003 8:51 AM
To: 'Hudson, Alan'; EMC-pstc (E-mail)
Subject: RE: Acoustic noise calculations for multiple shelves
Alan,
here is a definition of dBa:
dBa: Abbreviation for decibels adjusted. Weighted absolute noise pow
;uV/m" means "micro-Volt per
meter")
To be clear, I would have to say that was thinking in terms of dBpw/m^^2:-)
> -Original Message-
> From: drcuthbert [SMTP:drcuthb...@micron.com]
> Sent: Thursday, January 23, 2003 10:51 AM
> To: 'Hudson, Alan'
ource there is a 3dB difference when doubling/halving
distances.
Good luck,
Paul Hare
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Hudson, Alan
Sent: Thursday, January 23, 2003 4:15 AM
To: EMC-pstc (E-mail)
Subject: RE: Acoustic noise calculations
: Thursday, January 23, 2003 2:15 AM
To: EMC-pstc (E-mail)
Subject: RE: Acoustic noise calculations for multiple shelves
John Woodgate wrote:
> The noises are uncorrelated (largely), so you add 3 dB, not 6.
Now I'm confused! I always thought it was noise *level* (similar to voltage
level) n
John Woodgate wrote:
> The noises are uncorrelated (largely), so you add 3 dB, not 6.
Now I'm confused! I always thought it was noise *level* (similar to voltage
level) not noise *power*, and hence it was 20*log(ratio) not 10*log(ratio).
So I've been using 6dB for doubling noise, not 3dB.
I'll n
tandard or for operator comfort?
Dave Cuthbert
Micron Tech
From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Wednesday, January 22, 2003 10:56 AM
To: Luttrell, Lyle; 'Gandler, Mark'; emc-p...@majordomo.ieee.org
Subject: Re: Acoustic noise calculations for multiple shelve
2:56 PM
> To: Luttrell, Lyle; 'Gandler, Mark'; emc-p...@majordomo.ieee.org
> Subject: Re: Acoustic noise calculations for multiple shelves
>
>
> I would further amplify on this comment. It is not just a 10 log vs. 20 log
> calculation. Sound power is the quantity o
p...@majordomo.ieee.org
>Subject: RE: Acoustic noise calculations for multiple shelves
>Date: Wed, Jan 22, 2003, 9:23 AM
>
>
> Mark,
> You need to know what type of level you are working with.
> Sound power level (re 1pW) of multiple sources is straightforward: 10*log(n)
> = 13
Subject: RE: Acoustic noise calculations for multiple shelves
Mark,
You need to know what type of level you are working with.
Sound power level (re 1pW) of multiple sources is straightforward: 10*log(n)
= 13 dB for n=20. This is essentially independent of measurement
environment.
Sound pressure
calculations for multiple shelves
Hello Group!
Imagine you are going to install 20 small chassis (shelves) in one rack in
Central Office.
If you know your acoustic noise level from one chassis, is it any way to
calculate total noise?
Sorry, if it is not the smartest question.
Please reply!!! Need
I saw a posting which said add 6dB for a factor of 2. That is incorrect; when
you are dealing with sound. My apologies to this poster; no disrespect
intended.
When dealing with sound and power, add 3dB for a factor of two.
A factor of two only works out to 6dB if you are dealing with voltage
I read in !emc-pstc that Neil Helsby
wrote (in <20030122.8281...@mis.configured.host>) about 'Acoustic noise
calculations for multiple shelves' on Wed, 22 Jan 2003:
>The simple answer is that the result will be logarithmic – double the
>noise and you add 6 dB.
The n
The simple answer is that the result will be logarithmic – double the
noise and you add 6 dB. In practice it probably isn't and neither will
the on-site result when compared to your office measurements unless all
conditions are identical.
We measure the audio noise (mainly from fans) from our
emc-p...@majordomo.ieee.org
Subject: Acoustic noise calculations for multiple shelves
Hello Group!
Imagine you are going to install 20 small chassis (shelves) in one rack in
Central Office.
If you know your acoustic noise level from one chassis, is it any way to
calculate total noise?
Sorry, if it is no
Hello Group!
Imagine you are going to install 20 small chassis (shelves) in one rack in
Central Office.
If you know your acoustic noise level from one chassis, is it any way to
calculate total noise?
Sorry, if it is not the smartest question.
Please reply!!! Need an answer!!!
Thanks,
Mark Gandler
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