Sound intensity - How to deal with decibels?

  • #1
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I was looking up the maximal amount of noise allowed by current laws, that one can produce. I found that in my region one can produce sounds of up to 45 dB in the period from 22 pm to 7 am.

But, it seems evident that the decibels fall off as we distance ourselves from the source. So shouldn't that limit of 45 dB come with a specification of the distance from the source?

Or if I'm at home and my decibelimeter marks more than 45 dB, can I call the police anyway?
 

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  • #2
BvU
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No lawyer. But the 45 dB is to be measured at the receiving end: your ears.
Irrespective of the distance to the source.
But you have little chance of police enforcing such regulation.
 
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  • #3
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But you have little chance of police enforcing such regulation
yes :frown:
unfortunately.

but it is always good to have an idea of how loud it is before calling them.
 
  • #4
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But you have little chance of police enforcing such regulation.
I have had them enforce such regulations against construction companies that were working too early on a regular basis.
 
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  • #5
berkeman
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from 22 pm to 7 am.
I think you mean 2200 hours to 0700 hours (10PM to 7AM). :smile:
one can produce sounds of up to 45 dB
Such a measurement would be at a receiving location, like on the public sidewalk outside a house, or at your house next to a noise source.

Do you have a sound meter? There used to be inexpensive ones available from Radio Shack (in the US) a number of years ago (I still have mine somewhere)...

1589671386711.png
 
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  • #6
Vanadium 50
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. So shouldn't that limit of 45 dB come with a specification of the distance from the source?
It should. It probably does. But since you didn't give us a reference to your source, why are you asking us what it says?
 
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  • #7
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I think you mean 2200 hours to 0700 hours (10PM to 7AM). :smile:
:DD
Sorry, in our country we use 24 hours format, so I had in mind 22h.
Do you have a sound meter?
I downloaded an app that measures the dB. I know it's probably not as accurate as one more professional device like the one type you mentioned, but it helps in concluding whether or not the limits have been reached.
 
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  • #8
berkeman
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I downloaded an app that measures the dB. I know it's probably not as accurate as one more professional device like the one type you mentioned, but it helps in concluding whether or not the limits have been reached.
Hah, yes! I spaced the smartphone option. Duh! :doh:

My Radio Shack meter had 2-3 weighting options on it -- does your phone app include that, and does your local noise measurement law you allude to include which audio weighting should be used for the measurement?
 
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  • #9
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does your phone app include that
No, it only shows a gauge and a list containing references for intensities. FOr example, 40 dB corresponds to a residential area.
does the measurement law you allude to include which audio weighting should be used for the measurement?
No, they only mention the amount of decibels for the time period. But as it seems, this is not unique to my country, these two from India and Australia are similar:

https://economictimes.indiatimes.co...ent-types-of-gensets/articleshow/69094804.cms

https://www.lendi.com.au/inspire/lifestyle/know-your-property-rights-noisy-or-disruptive-neighbours/
 
  • #10
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No, it only shows a gauge and a list containing references for intensities. FOr example, 40 dB corresponds to a residential area.

No, they only mention the amount of decibels for the time period.
The one I looked at said dB(A). The A is the weighting.
 
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  • #11
DaveE
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Since this is a physics forum, then yes, absolutely the distance should be specified. But not everyone that writes laws knows physics...

This is from my city's building codes:
"Noise:
No individual piece of equipment shall exceed 110 Dba, measured 25 feet from such equipment.
Noise level at any point outside of the construction property plane shall not exceed 110Dba. "
 
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  • #12
davenn
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  • #14
Merlin3189
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IMO dB is probably the most abused "unit" around. (*)

It can be used well (I avoided saying "properly") as in Offcom licences, "all power levels are expressed as dB relative to 1 W", then each number is labelled dBW.
But generally the reference is implicit at best. Even when explicit the reference is often vague, eg. "almost silence". (At least they didn't say "silence", as that could really muck up the maths and make dB impossible.)

DecibelsDomestic.png

To be fair, if you have access to the ISO standard you can find out that near silence is probably an A-wieghted threshold of hearing for a standard listener, but the details tend to get lost when people produce tables like this. (Incidentally, IMO A wieghting is an honest attempt to do something useful, but even that has changed over the years.)
In electronics it was often unclear whether people were quoting power ratios or voltage ratios and you seem to get a similar confusion in sound, when people sometimes talk of sound pressure levels, rather than power levels.

Coming nearer to OP's issue, my bins are labelled with LwA dB, which does seem to be a well defined number, though I can't understand what it actually means. The rubbish bin and the green waste bin are both 99 LwA dB, but the recycling bin (middle sized of the three) is only 92 LwA dB. I don't know how they make all that noise? They usually stand there in silence (except for the birds.) If I drop something in when they're empty, there's a bit of a bump, slamming the lid makes about the same noise and the loudest is when I drag them across the gravel drive. If theyre talking about the noise when they're emptied, you can't hear the bin because the collection truck drowns out everything else.

I did find a reassuring explanation of sound levels in domestic appliances, summarised here
DecibelsDomestic2.png


(*) If you think there's a worse case (maybe SWARS, RMSWatts, WattsPMPO?) someone could start another thread and we could all let off steam about examples of misuse or our pet hate units?
 
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  • #15
anorlunda
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I have a question. Where there are laws limiting the magnitude of sounds, don't the laws specify how it is measured?
 
  • #17
sophiecentaur
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Anyone who has a serious problem with noisy neighbours should contact the environmental health officer. It's unlikely that the offender is only annoying one person and EHOs can be very helpful.
My son and a few of his neighbours complained about a noisy pub inClapham (London) and it had to close, after the EHO stepped in (with his expensive meter).
 
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  • #18
russ_watters
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But, it seems evident that the decibels fall off as we distance ourselves from the source. So shouldn't that limit of 45 dB come with a specification of the distance from the source?

Or if I'm at home and my decibelimeter marks more than 45 dB, can I call the police anyway?
Usually it is at the property line. Did you read the actual law?
 

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