Getting destructive capacity from decibels?

[Iustitia_Prime]

I'm working on a profile for a character with 300 decibel cannons. His twin sonic cannon shoots powerful, ear-splitting bursts of concentrated sound energy of up to 300 decibels. He can manipulate this energy in stereo (a result of the cannon's dual configuration) to shatter anything from a crystal wine glass to a cinder-block bunker.

So taking into consideration that it can shatter a bunker, I assume that makes these cannons around building level. But looking at this decibel scale-

http://www.makeitlouder.com/Decibel Level Chart.txt

278 (N)NUCLEAR BOMB, "BRAVO" TEST 15 MEGATONS, 1954, BIKINI ATOLL, MARSHALL ISLANDS -REF.2. ? (N)METEOR HITTING EARTH, "ARIZONA CRATER" SPEED WAS 44 MILES PER SECOND AND ABOUT THE SIZE OF A HOUSE AND MADE A CRATER ONE MILE IN DIAMETER 20 MT T.N.T. ? (N)NUCLEAR BOMB, 20 MEGATONS, SURFACE BURST CRATER IS 7392 FEET WIDE AND 792 FEET DEEP 282 (N)NUCLEAR BOMB, 57 MEGATONS HYDROGEN LARGEST EVER DETONATED, 1961 SHOCK WAVES CIRCLED THE EARTH 3 TIMES, FIRST ORBIT TOOK 36 HR 27 MIN. -REF.2. 282.042 db(Q) = dynamic wind pressure from a 10000 atm overpressure source 286 (N)MT. SAINT HELENS VOLCANO ERUPTION-BABY VOLCANO, BLEW DOWN TREES 16 MILES AWAY. COULD BE SEEN FROM OUTER SPACE ON THE SPACE SHUTTLE BLEW OUT SOME WINDOWS IN SEATTLE-TACOMA 200 MILES AWAY, 163 db (P) -REF.20. 294.09 (P) = 100000 atmosphere overpressure, dynamic pressure = 302.0488 db(Q) 296 (N)EARTHQUAKE 8.6 RIECHTER SCALE- GROUND MOVED UP AND DOWN 13 FEET. -REF.1.3. 1988 300 (N)HURRICANE ― AVERAGE, EXTREME ENERGY IS "DILUTED" BY COVERING 500,000 SQUARE MILES. ENERGY = APPROX. 1000 NUCLEAR BOMBS A SECOND.

Ok so, those things are pretty... intense compared to a bunker, at least in my mind. I understand that decibels like the richter scale are lagorithmic so maybe I'm misunderstanding what I'm reading here, or is it that dB is just a measure of sound and I can't draw any conclusions from the energy yield from it? Isn't sound a form of energy? And even if it is a lagorithmic scale, the richter scale has corresponding tnt equivalence. For instance, a 296 decibel rating is yielded from an 8.6 earthquake. 8.6 on the richter scale has a TNT equivalent of 119,786,623.7 tons.

Can I get a hand here?

 

[DontTalk]

Reading the wikipedia article on it as far as I understand: Decibel is (in accoustic) a unit of sound pressure, 300 decibel are equal to 2e+10 N/m^2 (if I have calculated that right based on wikipedias formula).

Now coverting pressure into energy is not really possible. Energy is force times distance, while pressure is force over area. So the units can not easily be converted in each other.

Given that the source is supposed to be a weapon specifically made to create soundwaves it can also not be compared to the sound explosion, earthquakes etc. make.

 

[Iustitia_Prime]

Huh. That's suprisingly a let down. I thought for a second a third-tier character was about to get a buff. Guess he's staying at building level. Thank you, though.