[Mohuska]

Gentlemen,

I regularly conduct acoustical measurements throughout industry and design acoustical dampening controls and want to point out somethings about your measurements.

We have used professional calibrated noise measurement instruments and compared against a number of iPhone/ipad or android apps and found the computer apps in general to be between 8 and 33% off. Most of these apps read high by about 12-16%.

It also matters where you measure as sound pressure will decrease by 1/2 with a doubling of the distance.

It also matters that your app scale is A weighted. This scale most closely represents the human ear. If you are reading C scale or unweighted, you will be substantially off from the true readings.

Finally, increased rpm will increase sound pressure level up through about 5500 rpm. After that, not a whole lot.