As I was getting interested in a new polisher I had kept researching decibel readings as I often try to work in my garage at night and prefer to avoid annoying neighbors. Polishing at night is beyond a rare occurrence but I was still intrigued. So when I got the Flex I knew I wanted to make this information known. I can't speak for the accuracy of this test but for reference OSHA recommends a maximum of 85 decibels constant for an 8 hour day. This adjusts for less time as decibels increase. Above that rating long term hearing may be affected. A 10 decibel increase is registered by humans as roughly twice as loud depending. So small changes and differences in readings can show noticeable change. I can't verify the accuracy of an iPhone's microphone in testing decibels or even how accurate of a reading the decibel app is, but I also have no issue trusting it based on no data saying it's incorrect and at the least it will show differences between polishers.
This test was done using an iPhone 6 3 ft away from a polisher facing upward with no pad on it.
Each polisher was turned on and tested 3 times via a locally sourced app. Each speed was individually tested with the polisher in an off position. Here is a photo of the app.
And the polishers up to the test.
The Porter Cable was also given a 6" backing plate but no difference was noted. And the final results!
Now I'm no expert, but hey I do have a piece of paper that says I got a college degree, not that it means much. So what do I draw from this? Ear protection probably wouldn't hurt honestly, and a decibel rating means little in regard to ergonomics and smooth operating but it is a factor. I hope this is a bit of interest to you all and if anyone has anything to add feel free to tack it on if this could be done better. Also data on the Rupes machine's or other machines wouldn't hurt either as I'm sure I can't be the only one interested in this.
This test was done using an iPhone 6 3 ft away from a polisher facing upward with no pad on it.
Each polisher was turned on and tested 3 times via a locally sourced app. Each speed was individually tested with the polisher in an off position. Here is a photo of the app.

And the polishers up to the test.

The Porter Cable was also given a 6" backing plate but no difference was noted. And the final results!

Now I'm no expert, but hey I do have a piece of paper that says I got a college degree, not that it means much. So what do I draw from this? Ear protection probably wouldn't hurt honestly, and a decibel rating means little in regard to ergonomics and smooth operating but it is a factor. I hope this is a bit of interest to you all and if anyone has anything to add feel free to tack it on if this could be done better. Also data on the Rupes machine's or other machines wouldn't hurt either as I'm sure I can't be the only one interested in this.