How do I calculate the noise level I am exposed to ,0.6m from the exhaust pipe (ride-on lawnmower-source)?
Eagle asked:
The manufacturer’s information states that the A-weighted sound power level (SWL) of lawnmower is 93dB
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The manufacturer’s information states that the A-weighted sound power level (SWL) of lawnmower is 93dB
What does A-weghted sound power level (SWL) mean
September 2nd, 2009 at 3:33 pm
Sound measurements
Sound pressure p
Sound pressure level (SPL) as in audio
Particle velocity v
Particle velocity level (SVL)
(Sound velocity level)
Particle displacement ΞΎ
Sound intensity I
Sound intensity level (SIL)
Sound power Pac
Sound power level (SWL) as in engine or washing machine ect
Sound energy density E
Sound energy flux q
Acoustic impedance Z
Speed of sound c
Sound power level or acoustic power level is a logarithmic measure of the sound
September 3rd, 2009 at 6:10 am
Sound attenuates with distance, but at less than a meter there will not be much reduction from the manufacturers specs.
Per most counties worker protection standards (unless you’re riding the mower for work, not mandatory, but it’s your hearing) anything over 85 dB (with the A weighting) requires hearing protection.
The A weighting refers to the SWL averaged across several frequencies within the range of human hearing and is the basis for worker protection standards (more info in the links)
I purchased my own ear protection through a local safety supply company and use it whenever I’m mowing the lawn, using the gas weed trimmer, chain saw, etc.
September 5th, 2009 at 4:45 pm
The best way to measure any sound level is with a sound level meter. Example of a link to one is in the radio shack website referenced below. The problem is that small distances, wind, age/maintenance of your lawnmower, etc. could signficantly change the ACTUAL sound reaching your ears. Measuring it is the only way to get a “real” value.
A-weighted sound level has to do with the fact that human ears are have different sensitivies to sounds at different frequencies. A-weighted sound levels account for this - it’s actually acceptable/safe to have higher amplitude sound waves below 1 KHz or above 4 KHz than in that range since human ears are less senstive outside of that range.
More info on A levesl is on the first engineeringtoolbox page below.
The second link below suggests that even 93 dB is too long for any length of time, so ear protection should be considered.
September 6th, 2009 at 8:09 pm
The SPL for you mower should be quoted at 93dB’s at so many meters in distance. For every doubling of the distance you can lose 3dB from the level.