Quiet-List 1997

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Re: Measuring noise



Eric,

>      Good point. How about a scale that weights lows, mids, and highs 
> based on the average person's degree of annoyance? The dB(A) scale 
> omits the annoying lows. Some combination of the (A) and (C) would 
> probably be an improvement.

I think that when the A scale was definitively adopted as THE scale,
many years (and even decades) ago, the addiction to oversized bass was not
yet established. 

It has been long accepted that the A scale correlates reasonably well with
hearing risk, with annoyment, and with speech interference. OK, but the 
second item shouldn't be considered isolated from the "average" noise
prevailing in a given historical time. Indeed, nobody would dare say that
a single 4 KHz tone  rating 80 dBA is equally annoying than the 80 dBA
noise of a highway (for those folks not acquainted with frequency values,
4 KHz is a highly annoying, deeply penetrating whistle, and 80 dBA of such
certainly would drive anybody crazy after a few minutes). So, if some time
in the future 4 KHz tones come to considered quite cool for the noise
makers, the A scale would certainly fail to predict annoyment.   

So, I think that the A scale, which is so successful as regards to hearing
risk assessment (note for instance the "Levels Document" by the EPA, or
the ISO 1999 Standard, both of which are first rank documents acknowledging 
this fact), isn't so successful regarding annoyment. That's the main 
reason why it yields misleading results when used to evaluate the annoying
potential of "modern", bass-boosted music.    

I think a scale should be developed taking into account the 
slowly-varying-in-quality noises prevailing at different times. Today, 
major community noises are those coming from traffic, aircrafts and
so-called "modern" music. All of them contain unbalancedly large amounts
of low frequencies, so the scale to use nowadays should probably boost the
importance of low frequencies.  

To summarize, we should no longer stick to the concept that a single
figure is able to account both for hearing risk and annoyment. We
should start to acknowledge that not only hearing-damaging noises are
annoying. 

Best wishes.

Federico Miyara

PS: Merry Christmas!

  

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