How Does Sound Work?

[barry1010]

If I am listening to my music playing at 60 decibels on one radio and turn a second radio on 40 dB, is the music louder?

[ToraToraTora]

There is an interference effect so it would get a bit louder but it's not as simple as adding the two.

[Ellipsis]

Yes, as long as you can hear them both. For example, if the second radio was 1000 miles away, then no. If the second radio was right next to your ear, then yes.

[Hymie]

Hardly, because a 3dB increase represents a doubling of the sound, so at 20dB less you’ll hardly notice the second sound source.

[barry1010]

It's not like adding half a pound of flour to a pound of flour, is it?
The things my grandchildren expect me to know

[Ellipsis]

Actually, I'll leave this for somebody who knows what they're talking about! I'm not sure that anybody does as yet. For example:

> https://rnid.org.uk/information-and-support/ear-health/protect-your-hearing/how-loud-is-too-loud/
> Noise is measured using the decibel (dB) scale, which reflects the sensitivity of human ears to different levels and frequencies of sound.
> Here are some examples:
> 0dB: the quietest sound a healthy human ear can hear
> 40dB: a quiet library
> 60dB: ordinary spoken conversation
...
> 130dB: an aeroplane taking off 100m away.

The last one is interesting ... "100m away". But it looks like there are different meanings of "decibels". See https://en.wikipedia.org/wiki/Decibel

[barry1010]

I'm more confused than ever.

[THECORBYLOON]

I've worked out the new level would be 60.04dB.

[barry1010]

Thanks, Corby - would that be noticeable to a casual listener?

[ToraToraTora]

It may also be of interest to point out that the decibel scale is logarithmithic.

[barry1010]

And Whooosh!

[ToraToraTora]

You did maths at school surely barry?

[barry1010]

Not logarithms. It would have been a waste of the teacher's time trying to teach me.

[ToraToraTora]

well it's only another angle on exponents barry, 10^2=100 - thus Log 100 = 2 - the index to which you must raise 10 by (the base) to get 100 is 2. So Log is just asking what exponent do I need to raise the base by to get 100 (in this case), simples!

[THECORBYLOON]

BARRY, the Richter Scale, used to measure the intensity of earthquakes is logarithmic.

10⁰ = 1
10¹ = 110
10² = 10 ×

[bobbinwales]

think thats come out not how you meant corbeyloon

[bobbinwales]

10⁰ = 1
10¹ = 10
10² = 10 × 10 = 100

[ToraToraTora]

What the nitpicker said it wrong nooooo! What kind of nitpicker would I be if I corrected the nitpicker! PMSL!

[weecalf]

I’d say it was less acause your brain would have work out both sound and compare them so the music could be 50 at most

[THECORBYLOON]

Pressed "answer now" in error...

10⁰= 1
10¹= 10
10²= 10×10= 100
10³= 10×10×10= 1,000
...
10⁶= 10×10×10×10×10×10 = 1,000,000
10⁷=10×10×10×10×10×10×10 =10,000,000

The wee numbers are the powers and when comparing the sizes of earthquakes, the difference between the two numbers shows how much more powerful one is compared to another.

Say there's one with a magnitude of 7.5 on the Richter scale and another that's 5.5 on the scale.

A difference of two doesn't sound a lot but a 7.5 earthquake is 10² or a hundred times more powerful than a 5.5 one.

The same applies to 3.5 compared to 1.5, the difference is two so the 3.5 earthquake is a hundred times more powerful than the 1.5 earthquake.

[Peter Pedant]

my physics master did his thesis on phonics and sound but cdnt really teach us

Because the decibel scale is a logarithmic scale, if we have two different sound sources combining together we can't simply add the sound pressure levels - what we have to do is to add the intensities. That means we have to convert our decibel values into intensities (with units of W/m2).

so the pressure wave in the ear which assaults the ear drum is additive ( and is a power / area )

and we did it in CGS watts / cm2

BUT the sensation of loudness ( which should relate to watts /cm2 - doesnt. Shallow U shape.

a power X watts / cm2 at 1000 cps, does not sound as loud as the same power at 1500 cps

told you he cdnt explain it

piddy - he had done a thesis on it and cdnt explain it to 18 y olds