I’m getting older, and I certainly don’t want to damage my hearing any more than necessary. So to that end I want to at least get a ballpark estimate of just how loud it is in the data centers I work in. The free Sound Meter app is nice because it compares the current reading to everyday items. (Well not that many people are close to the Space Shuttle, but you get the idea anyway.) I would strongly consider borrowing a real sound pressure meter so that you can calibrate this tool, but even without calibration it’s better than nothing.