MrNoise!

Mr Noise turns your iOS device into a simple sound level meter. With it, you can easily measure sound pressure level. Our app creates live decibels graph so you can visualized every sound, and its free Mr Noise can measure peak sound levels of up to approximately 130 dB on iOS 5+ and 105 dB on iOS 4 (peak levels are device/microphone dependent).Mr Noise has not been shown to meet ANSI or IEC standards for sound level meters.