[*_ash_*]

Slightly unusual question (I've not been on the sauce honest), but there's always someone on here who can explain something in plain English. I'm struggling with a piece of writing, because I don't quite understand noise level measuring.

So..

For example. 10 people are stood together. All with foghorns.

1 person sounds their foghorn. For simplicity let's say it produces 100dB from 100 feet away.

Now a second person joins in.

then a third, etc, until all 10 are sounding them.

-

What happens to the dB rating? Assuming all the foghorns are the identical, is it a simple as being the same? Obviously it's not 10 times as loud in the rating as dB rating doesn't go that high.

It may come as a surprise, but I couldn't find a foghorn analogy on Google

I definitely should have paid more attention in school, though I don't recall studying logarithmic scales

[bizzle]

Chuffinel Ash, thats a hardcore Q) at this time in the morning. Are you qualifying for a PHD

[*_ash_*]

Originally Posted by bizzle

Chuffinel Ash, thats a hardcore Q) at this time in the morning. Are you qualifying for a PHD

Not quite Ms.

Where's heyesey when you need him! He used to be around at this time of night.

Actually Bizz, I don't think its probably a hard question. I just don't know the answer.

[bizzle]

That makes two of us, Ash. Why could you not ask a easier question

[*_ash_*]

Originally Posted by bizzle

That makes two of us, Ash. Why could you not ask a easier question

I could ask an easier question, but I'd be more likely to know the answer, hence more likely not ask it.

[sausagefinga]

Originally Posted by *_ash_*

What happens to the dB rating? Assuming all the foghorns are the identical, is it a simple as being the same? Obviously it's not 10 times as loud in the rating as dB rating doesn't go that high.

The 'dB scale' is a logarithmic one, similar to how we interpret sound levels, and therefore can double in intensity without doubling the dB number.
So 10 times louder than 100dB could be somthing like 180dB.

(I am completely guessing the numbers here and am sure somebody will be along in short order to put me right.)

As for how loud 10 fog horns would be? I don't know, i just wanted to say that thinking about 1000dB would be incorrect.

[f0rd]

Originally Posted by *_ash_*

Slightly unusual question (I've not been on the sauce honest), but there's always someone on here who can explain something in plain English. I'm struggling with a piece of writing, because I don't quite understand noise level measuring.

So..

For example. 10 people are stood together. All with foghorns.

1 person sounds their foghorn. For simplicity let's say it produces 100dB from 100 feet away.

Now a second person joins in.

then a third, etc, until all 10 are sounding them.

-

What happens to the dB rating? Assuming all the foghorns are the identical, is it a simple as being the same? Obviously it's not 10 times as loud in the rating as dB rating doesn't go that high.

It may come as a surprise, but I couldn't find a foghorn analogy on Google

I definitely should have paid more attention in school, though I don't recall studying logarithmic scales

edit: rewriting as i was not clear

I am going to ignore aspects like source of the sound, and phase difference.

So if there are ten of them sounding at the same time all at 100 dB the total would be around 110 dB

The formula simply is (where every source is the same sound pressure) to work out the level difference is 10*log*n

n = the number of same rated sources.

So 10*log*10 = 10 dB

So the increase is 10 dB in total 110 dB.

Yeah it's all to do with logs, I could demonstrate adding up multiple sources of different sound pressure levels later if you want, but it will be equations and walking through them as I am terribly bad at putting things into analogies.

[*_ash_*]

Originally Posted by sausagefinga

The 'dB scale' is a logarithmic one, similar to how we interpret sound levels, and therefore can double in intensity without doubling the dB number.
So 10 times louder than 100dB could be somthing like 180dB.

(I am completely guessing the numbers here and am sure somebody will be along in short order to put me right.)

As for how loud 10 fog horns would be? I don't know, i just wanted to say that thinking about 1000dB would be incorrect.

Thanks Sausage, this is a start.

Yeah I know that dB levels don't go above a certain number, 200 ish I think. (easy to find if I google that).

To add to what you've said. The figure might be 180dB for 10 fog horns. We're getting somewhere now to my question. If we can establish that 10 foghorns is louder than the sound of 1 foghorn, hopefully someone can add the rest. i.e how many foghorns required to make the highest level of noise. If that is possible.

[dosxuk]

dB's are a ratio, rather than a fixed measurement, and are also logarithmic in scale.

There is an equation on wikipedia for calclating the sum of several sources: http://en.wikipedia.org/wiki/Sound_p...ressure_levels

Edit:

Originally Posted by Ash

Yeah I know that dB levels don't go above a certain number, 200 ish I think. (easy to find if I google that).

There's no reason for dB's to stop at 200 (and they don't). It's just very difficult to make (& measure) a sound that loud.

[*_ash_*]

Originally Posted by f0rd

I am going to ignore aspects like source of the sound, and phase difference.

But a simply time you double the sound pressure wave, add 3 dB.

So if there are ten of them sounding at the same time all at 100 dB the total would be around 110 dB.

Aha. I never thought of wiki'ing sound pressure. Thanks ford.

I've found a source of that, which is pretty good. This one

[f0rd]

Originally Posted by *_ash_*

Aha. I never thought of wiki'ing sound pressure. Thanks ford.

I've found a source of that, which is pretty good. This one

Yeah that is a good source I used it quite alot in my undergraduate degree alot, to be honest I had to dig up my notes didn't think to go to the site

But if you need any more help on audio engineering drop me a line.

[*_ash_*]

Originally Posted by dosxuk

dB's are a ratio, rather than a fixed measurement, and are also logarithmic in scale.

There is an equation on wikipedia for calclating the sum of several sources: http://en.wikipedia.org/wiki/Sound_p...ressure_levels

Edit:


There's no reason for dB's to stop at 200 (and they don't). It's just very difficult to make (& measure) a sound that loud.

Yes, it seems you are right. Though I can't imagine a limitless SPL in this equation- (edit, which doesn't work in here ).

Sound pressure level (SPL) or sound level Lp is a logarithmic measure of the rms sound pressure of a sound relative to a reference value. It is measured in decibels (dB) above a standard reference level.

L_p=10 \log_{10}\left(\frac{{p_{\mathrm{{rms}}}}^2}{{p_{\ mathrm{ref}}}^2}\right) =20 \log_{10}\left(\frac{p_{\mathrm{rms}}}{p_{\mathrm{ ref}}}\right)\mbox{ dB} ,

where pref is the reference sound pressure and prms is the rms sound pressure being measured.[1]

Sometimes variants are used such as dB (SPL), dBSPL, or dBSPL. These variants are not recognized as units in the SI.[2]

The unit dB (SPL) is often abbreviated to just "dB", which can give the erroneous impression that a dB is an absolute unit by itself.

The last line indicates where I why going wrong.

[f0rd]

Also I should add, you can cheat when adding them up just by converting dB to watts, adding the watts up normally, then with that just use 10*log(P1/P2).

[*_ash_*]

Originally Posted by f0rd

Yeah that is a good source I used it quite alot in my undergraduate degree alot, to be honest I had to dig up my notes didn't think to go to the site

But if you need any more help on audio engineering drop me a line.

Thanks Ford.

One question, as I've just quoted my misunderstanding to dosxuk.

Is it possible then to have enough foghorns to reach the maximum level to which we can easily record?

Looking at the graph on the wiki page, it's not constant, [and the way I see it], it means you would have to have almost an infinity of foghorns to reach it

(by the way, I've got the info I need now, for my analogy in my writing, but I'm being a geek now )

[*_ash_*]

To answer my last post, I've just seen your updated earlier post.

[foxforcefive]

Just resist the foooooooooooook en fog horns and the world will be a happier (and quieter) place.xx

lurve you.xx