I am in need of help: equations and references

[GutZ]

Thank you, thank you, beforehand.

 

This whole thing is about sound so...

 

First I want to find out, if I have a sound source like a speaker. I want to figure out how far it travels and how much ...I guess vibratory energy it looses due to (I guess it would be called attenution) length of travel in air, then through other material.

 

I can find like the material stuff, but I don't know where to start really....

 

As you can see I am a bit confused so maybe some can help me out here...

 

Because I can never tell if sound coming from my APT is heard elsewhere, and I hate being anxious all the time but I hate to disturb people too so, If I can figure it all out I can feel better about it!

[m4rc]

If you require a precise answer then it will be difficult

 

The first effect is that sound spreads out as it moves away from the source

The other cause for attenuation is absorption which will be more important in materials. In matter, I suppose that the absorption of sound waves will decay exponentially with distance.

 

The spreading out of the wave:

The reduction in intensity due to this effect is I=P/A , where I=sound intensity, P=power of the source of sound, A=area over which the sound is spread over.

 

The intensity of sound can be measured in watts per square meter. The threshold of hearing is about 10^-12 W/m^2, whispering is at 10^-10 W/m^2 and a rock concert may be 0.1W/m ^2.

 

If you are in a wide open space, then you the area you will use is the area of a sphere with a radius equal to the distance between you and the source. A=(4/3) pi r^3

 

It would be difficult to calculate the attenuation of sound with distance in buildings because sound can reflect of walls and be channeled down hallways.

 

Depending on what you're trying to calculate, it might be important to know that the ear's sensitivity to sound intensity varies with sound intensity. When comparing perceived sound intensities, you should express the intensity in decibels where:

 

Intensity in db= (10dB) Log(I/10^-12W/m^2)

[GutZ]

Very nice, thank you, I believe that is all the information I will ever need hehe. thank you again.

[timo]

Just in case you'd blindly plug in without taking care of the units: 4/3 pi r³ of course isn´t the surface of a sphere but the volume of it.

[GutZ]

Just in case you'd blindly plug in without taking care of the units: 4/3 pi r³ of course isn´t the surface of a sphere but the volume of it.

 

I am not an idiot! lol, I maybe in college, but they do teach us some stuff. Actually your right, you never know.