This app was removed from the App Store.
Sound Level Application
iOS iPhone Entertainment
Sound Level provides a simple, fun way to measure audio volumes in your environment. The app shows the approximate dB (decibel) level, also known as Sound Pressure Level (SPL).
This app is intended for personal and entertainment use only, not for professional dB/SPL measurements, for which you should buy a real sound meter from your local electronics store. The app provides relative, approximate values only.
We've included some useful statistics about the measured volumes, including Average, Peak, Peak Hold, current dB level, maximum, and minimum values. These can all be quickly reset by tapping the Reset button, or they can be "frozen" by tapping On/Off.
If you wish to use an external microphone, or if you find that the dB reading is a bit off when compared with traditional analog SPL meters, you can calibrate the app using the Settings screen. For example, a hyper-sensitive microphone might give you a dB value that is too high, so you'd add a negative Trim value to the dB reading to adjust. Calibration settings ("Trim") are saved internally in the app.
To adjust the calibration, tap the "Settings" button, and then adjust the value based on whether you are using an internal microphone (iPhone users) or an external microphone (iPod Touch users).
Please note that this application requires an external microphone for use with the iPod Touch.
An approximate guide to decibel level safety:
150-160 = Eardrum rupture
140 = Aircraft carrier deck.
130 = Jet take-off (100 meters), gun blast at close range.
120 = Human pain threshold, loud rock concert.
110 = Serious hearing damage if sustained for more than 1 hour.
100 = Serious hearing damage if sustained for more than 8 hours.
90 = Likely hearing damage if sustained for more than 8 hours.
80 = Potential but unlikely hearing damage if sustained for more than 8 hours.
70 = Just annoying, but probably safe.
60 = Typical conversational volume.
50 = A quiet, library conversation.
40 = A whisper.
30 = Barely audible sound.
20 = Threshold of human hearing.
The volume meter calibration has been reverted back to what it was in mid-2010 due to an error in the re-calibration formula. We're re-visiting the calibration now with some more precise SPL meters from Radio Shack to try to get this more accurate!