This calculator can be used to predict the distance from an open detonation at which 140 decibels (dB) could be expected to be achieved. The 140dB level is widely used as a "safety cutoff" for exposure to impulsive noises while using hearing protection.
A second related parameter is the critical distance for eardrum rupture.
Noise Prediction Range to 140dB
The equation for this calculation is as follows:
Distance = 215(NEQ)1/3