Help with noise

[Mr_Brushcutter]

Hi

Trying to work something out for work in regards to noise. Got lots of machines hedge cutters chainsaws etc. I've got noise data for them but i'd like to know how loud they are over set distances.

e.g. Husky 365 chainsaw
Sound power level measured dB(A) 111
Sound power level guaranteed Lwa dB(A)114

How could i work out how loud it would be a 1m 5m 10m 15m etc

Thanks

Andy

 

[OKNEY1LZ]

Inverse Square!

Hello all!

This is a very informative and entertaining site. I hope to find time to write a proper introductory post over the weekend. But I thought I would jump in here to get my feet wet. Got to start somewhere. Anyway here goes!

To find out different sound energy levels you generally use the Inverse Square Law. Which in a nutshell goes like this: Doubling the distance results in the sound energy being one quarter of what it was at the original point of measurement. Here are a few sound related sites to give you a better understanding of how this and other equations work in sound energy calculations:

http://www.windpower.org/en/tour/env/db/dbdef.htm -Site is about wind turbines, but a good general overview.


http://www.xs4all.nl/~rigolett/ENGELS/equipment/spcalc.htm -This one is a on-line calculator that you may find of interest.

Hope this information helps you out!


Lawrence

 

[Jim1NZ]

Chippers are 120+

 

[iain]

our chippers 118+

 

[timberwolf]

SImple way is subtract 6db every time distance doubles, but for your purpose you need to know at what distance the rated sould level is given. It seams many things are rated at 3 feet/1m or 10 feet/3M

But in real life it is not so simple. 6db fore each doubling of distance may be close to right in an open field with soft ground. But if there are buildings, or other hard surfaces in the area the sound levels will have peaks and valleys. Temprature and atmospheric conditions play a role also.

January -20 degrees and sound travels for miles
July, Warm, foggy, light rain, leaves on the trees, and sound is dampened dramatically

 

[CJ-7]

Go to Radio Shack and get a digital sound meter http://www.radioshack.com/product.asp?catalog_name=CTLG&product_id=33-2055 . Many uses and very informative. You can even use them for setting up a big stereo or home theater.