Needs a calibration method. – Decibel - Accurate dB Meter Review

I used this app first at a rock concert and it seemed to register correctly- around 110db. However, late at night at home with almost no noise around, it showed about 50-60db! Clearly, it is over reading at lower decibels. Wish there was a way to calibrate the app.
Review by Jumbara on Decibel - Accurate dB Meter.