First use of Gibb's Rule #73: Never meet your heroes.
As McGee (Sean Murray) and Kasie (Diona Reasonover) are testing the Sonar, they measure 311db rather than the official limit of 235db. The difference is 76db, which implies the sonar is generating 42million times as much power. Each 3db means twice as much power measured in watts. 6db = 4x as much power. 9db = 8x, etc.
Kasey tells McGee that the sonar is limited to 235dB. 140dB is a jet engine at ten feet. 235dB is 3,160,000,000 megawatts per square meter of energy. Or in easier to understand terms, each square meter receives as much energy as the total electricity generating capacity of 2,700 USAs.