Have Question, search disabled, db drop per foot???

[ritelec]

Hi, playing a back yard party.

Town says 65 db at neighbors property, till 10pm.......10pm to 7am 50db.

We've been comfortably playing in my room at about 85-95.


Is there a give or take db drop per foot, or meter? All open with grass, no to few trees. One neighbors about 50' away, the other about 150' away.

Thank you.

[Dange]

double the distance is -6dB. So if at 1ft from the source the sound is 56dB then at 2ft the sound level will be 50dB in freefield.

This does the math(s) - Damping of sound level with distance - decibel dB damping calculation calculator distance versus sound reduction free field loss - decrease drop fall in sound over distance versus dB sound at different distances microphone calculator distance drop ra
You'd need to know that you're definitely at 85-95dB too. I'd also warn the neighbo(u)rs beforehand.....

[ritelec]

Originally Posted by Dange

double the distance is -6dB. So if at 1ft from the source the sound is 56dB then at 2ft the sound level will be 50dB in freefield.
You'd need to know that you're definitely at 85-95dB too. I'd also warn the neighbo(u)rs beforehand.....

Thanks Dange.

-6/doubled....got it.

And the neighbors. I agree, let them know what's going on, invite them over for a bite and some cocktails.


Thanks again.

[ritelec]

Wait.I don't have it.

As in the example of 1 foot is 56db, 2 foot is 50 db.

4 foot would be 44db? Or, 2 foot doubled (2 (2) original + the 2 doubled (4) = 6 foot) + the original distance would be 44db.

[boggy]

Originally Posted by ritelec

Wait.I don't have it.

As in the example of 1 foot is 56db, 2 foot is 50 db.

4 foot would be 44db? ......

Yes!
... 8foot will be 38dB
....16foot will be 32dB

etc...

Cheers

boggy

[ritelec]

"is lowered by 6 db when your distance from the object doubles, or conversely when the db reading increases by 6 db when distance is decreased by half"

???

1=56
2=50
4=44
8=38
16=32


???



OK...Just read reply, thanks boggy... and Dange.

[ritelec]

I sat in his yard yesterday with my trusty radio shack spl meter.

The location is a bit in the country and you may hear a sound of a passing car very far away.

Just sitting there, the spl read 65 db (should that be considered noise floor?)..

We went in his basement and measured the volume of his PA that we are going to use. Reading was about 98db.

I guessing the spl measurements will change because we will be out doors, but my question is...

Is the spl additive?
Will the spl increase with the PA starting at 65db?
Or will the PA spl and original 65db ambient spl be the same until a threshold is met (65), and then it would increase from there?


Just wondering.

-rich

[juaco]

If you add up two sources with same SPL reading, say 65dB, the total SPL will be 68dB. That´s a 3 dB increase, and double sound pressure. SPL is additive, but not in the traditional way(65dB + 65dB equals not 130 dB, as I wrote above).
Hope this helps out, and sorry if I misunderstood your question, english is not my mother language.

[DanDan]

I think the 6dB with doubling of distance applies to an omni source radiating equally in all directions.

Most (wordly) situations are in a half sphere. So the loss would tend to be closer to 3dB.

DD

[nosebleedaudio]

Go to Radio Shack and get a SPL meter and check it yourself...

[jhbrandt]

Originally Posted by DanDan

I think the 6dB with doubling of distance applies to an omni source radiating equally in all directions.

Most (wordly) situations are in a half sphere. So the loss would tend to be closer to 3dB.

DD

Yes, this is important... this difference in level varies INDOORS.

In an enclosure, depending on treatment, you will have what is called 'critical distance'. This is where reflections from surfaces combine so that the level remains the same after a certain (critical) distance.

So the inverse square... does not apply.

Cheers,
John

[ritelec]

Originally Posted by nosebleedaudio

Go to Radio Shack and get a SPL meter and check it yourself...

Originally Posted by ritelec

I sat in his yard yesterday with my trusty radio shack spl meter.

Curious to take measurements with the PA and inst. are playing.

Originally Posted by jhbrandt

INDOORS.
depending on treatment, you will have what is called 'critical distance'. reflections from surfaces combine so that the level remains the same after a certain (critical) distance.

Thank you. Wondering what the spl will be when the sound is not confined.
We'll find out.

Interesting, the town did post spl at frequencies.
http://www.ecode360.com/documents/CH...0Table%20I.pdf
http://www.ecode360.com/documents/CH...Table%20II.pdf