Re: Measuring Noise

[Chris England <cengland@xxxxxxxxxxxxx>]

David Staudacher wrote:
> 
> On Thu, 18 Dec 1997 09:44:57 -0800,
> Chris England   <cengland@earthlink.net> wrote:
> 
> >Sensitivity to sound levels can be estimated by using factors that
> >include both the sound level and the "white noise" character...
> >I have developed a rating method for noise based on this approach.
> 
> Please elaborate.  I'd like to hear more about your method.  Does
> it yield a quantity based on some unit?  Does it isolate a given set
> of conditions into various categories (i.e. minimal/moderate/extreme)?
> 
> David Staudacher - quiet@igc.org
> 
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Thank you for noting my message on rating noise.  My friend Gertrude (b.
1914) advised me that people expect a simple numerical rating for just
about everything (thumbs up, four stars, etc.).  On the quiet list,
there is no agreement that measurements are a valid means of rating
noise.  If not measurements, then what?  

In the 1970's, noise was taken more seriously.  In the
anything-goes-for-commerce 1980's, these laws were left unfunded (at
least by the US Congress and by the State of California where I work). 
The more serious noise work in the 1970's sometimes included "area
charts" in which the % of time at a dB level was plotted against the dB
level.  With a little experience, this type of chart gives a very good
and very quick evaluation of the noise environment.  Now, how to reduce
this to a rating?

I divide the chart into regions (but not simple vertical cuts), label
the regions from 1 to 6, and determine a rating.  The "slope" of the
region determines the "white noise" character.  It's a Master's thesis
to do the full justification, perhaps a Ph.D. thesis to assemble
confirming data.  That's the problem.  It takes a lot of time and effort
just to get agreement on a rating system.  

The ratings I use are (1) very quiet, (2) quiet, (3) intermediate, (4)
transitional, (5) noisy, (6) very noisy.  There is good agreement on the
qualitative ratings.  People living in a 5-rated spot agree that it is
noisy;  those living in a 3-rated spot agree that it is neither noisy or
quiet.  One more thing.  I separate day and night.  The definitions of
"day" and "night" vary according to location.  In Los Angeles, I like to
use 6:00 a.m. to 8:00 p.m. for day.  This is based on the 24-hour noise
pattern in the area which is fully developed at 6:00 a.m.  For the east
coast, perhaps 7:00 a.m. to 10:00 p.m. is better.  In South America and
Europe, it would be different still.
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QUIET-LIST:   Internet Mail List and Forum for discussion of Noise Pollution,
Soundscape Awareness, and the Right to Quiet.     Email: "quiet-list@igc.org"
To subscribe, email "majordomo@igc.org" with message "subscribe quiet-list".
For info, send message "info quiet-list" to same.
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