SoundMeter turns your iPhone into a sound level meter. Getting started is as simple as tapping the app icon in the Home Screen and tapping the Start button in the toolbar once SoundMeter opens.
For best results, SoundMeter should be calibrated before use. Sound levels may be off by 6 dB or more when using the default microphone sensitivity.
SoundMeter is not recommended for use with the built-in microphone of first-generation iPhones.
NOTE: SoundMeter has not been shown to meet ANSI or IEC standards for sound level meters.