1. Source:coolmath.com & The National Safety Council Threshold of hearing whispering Conversation Car interior Sewing machine Busy Traffic Screaming Child Diesel Truck Jack hammer Air drill Lawn mower Helicopter Snowmobile Inboard motorboat Sand blaster Fender amp @ 10” Auto horn Propeller aircraft Trumpet peak @ 5” Gun Shot Jet engine Rocket launch Everyday noise and recommended maximum exposure levels. A 5 dB reduction is about 30% quieter and is a 50% decrease in the risk! deciBel