Originally Posted by wbdvt
Ashley - thank you for the report. Even thou the db meter on the iPhone may not be entirely accurate for precise measurements, it was good enough to provide an objective measurement that did show a level decrease.
In sound measurement, near silence is 0 db and a sound 10x louder is 10 db. A sound 100x louder is 20 db due to the logarithmic function of the decibel. I will use the iPhone decibel app to measure before and after the install.
I did get into the camper today and verified I have a Ventline so install should be fairly easy.
Each 3db doubles the power, but we aren't talking watts; rather sound or in this case noise. And thanks Ashley!
Bell Labs came up with this easy logarithmic way to measure or calculate sound through a media, such as air or wire; loss through the transmission, actually. It is a ratio to power in to power out; zero isn't the absence of sound, but a reference or staring point. In the telecom world we consider the characteristics of the human ear; call it dba and state 1000hz at 1mw is 0db. With noise, in the air, it is a bit different.
The average home is about 40dbm... rustling leaves 10dbm... a jet at take off 120dbm. So the jet 12 times or 120 times louder than the leaves... no. Its a trillions time "louder".
From the old fan to the new one what does a reduction of 20dbm mean.
So Ashley your 40dbm might be a bit high if nothing is running in the trailer. The 80dbm from the old vent sounds slightly high, this would be about the sound in a closed car on the interstate, The reduction in noise to the new would make that about as loud as normal conversation. Which means the old fan would be competing with actual conversation, but moving away from the new one, there would be no competition to what you might be listening to.
Placing the "meter" on the counter, if you did, could cause higher readings. It should be around head height and farther way, but if it was the same for all three tests, it might be a good comparison.
The new fan producing 50dbm is believable, but not registering a higher reading with the new fan on high; not so much. I would think 60dbm in high would still be good.
So, the issue becomes how to interpret the numbers. 20dbm difference would indicate to me that the noise was reduced to a point around normal converstation from one more like a closed car on the interstate. It is quieter on high as the old one was running and it moves more air on its low setting. A good product for sure.