I was caught in an electric storm last night while camping. The time between flash and thunder must have been 3 seconds or less at least five times. (The nearest hill peak which could have been attracting the lightning, was about 160m higher than me and 600m away.) I found it quite scary, and found myself hoping very strongly that it would not strike anything closer than that hill peak 600m away. When that close it sounds like a like a bang, series of bangs, or a prolonged ripping sound. I covered my ears to protect them, it was that loud.
How close does a lightning strike have to be to be perceived at 140dBP (dB Peak Pressure), which is a level of noise which is unsafe for any period of time? (I would also be interested to know of any data on the greatest possible distance from a lightning strike for injuries other than permanent hearing loss, eg from debris flying out from the strike, but that is secondary.)