Decibel Level Comparison Chart
Commercial	Industrial	Residential	dB Level	Sones
Threshold For Hearing			0	0.00
Good Recording Studio		Breathing	10	0.29
		Rustling Leaves	15	0.41
		Whisper, Mosquito	20	0.57
Library		Living / Dining Room	30	1.15
Refrigerator Hum		Kitchen / Bathroom	40	2.30
Quiet Office		Home Office	50	4.59
		Birds at 10'	55	6.50
Conversational Speech			60	9
Piano Practice		Electric Shaver	60	9
Business Office		Piano Practice	65	13
Noisy Restaurant	Office area in plant	Street Traffic	70	18
Chamber Music		Barking Dog	75	26
Classroom		Alarm Clock	75	26
		Dishwasher	75	26
Airplane at 1 mile	Manual Machines	Vacuum Cleaner	80	37
OSHA Required Hearing Protection in Factory			85	52
Reception / Lobby Area	Handsaw	Garbage Disposal	85	52
Motor Bus		Telephone Dial Tone	85	52
Applause in Auditorium		Lawn Mower	85	52
Sustained Exposure May Cause Hearing Loss			90	74
Train at 100'	Farm Tractor	Teenagers Stereo	90	74
Music Practice Room	Electric Drill	iPod (volume level 5)	94	97
French Horn	Average Factory Noise	Blender	100	147
Orchestra	Diesel Truck	THX Home Theater	105	208
Computer Room	Printing Press	Train	105	208
Bass Drum	Heavy Truck	Power Saw	110	294
Dog Kennel	Power Mower	Baby Crying	110	294
Symphony Orchestra	Punch Press	Squeeky Toy to Ear	110	294
Pain Begins			120	588
Disco	Sandblasting	Shotgun	120	588
Rock Concert	Pneumatic Clipper	Air Raid Siren	130	1,176
Dragcar Racing	Military Jet	Shotgun	140	2,352
KISS Rock  Concert - Ottawa, CA July 15, 2009 136db	Aircraft Carrier Deck - Jet Takeoff		140	2,352
Chest Wall Begins to Vibrate			150	4,704
Ear Drum Breaks Instantly			160	9,408
Death of Hearing Tissue			180	37,632
Loudest Possible Sound in air @ sea level			194	99,309
Sones are calculated using the formula   sones = 10^[(dBA - 28) / 33.22]
http://www.phys.unsw.edu.au/jw/dB.html
The limit of 194 dB is caused by the atmospheric pressure at sea level. The decibel level is an indication of the pressure difference between equilibrium and crests and troughs in a sound wave. You can't create a trough (low pressure) with an absolute value greater than the ambient air pressure, so this is indicated to be the "loudest possible sound." But, keep in mind that the limit of 194 dB comes with seveal caveats. First, it is based on sound traveling in air. Furthermore, it assumes sound traveling in air at normal atmospheric pressure. Thirdly, I wouldn't really classify 194 dB as a "sound" since you can't really hear it, however, it can be described by the mathematics of sound waves. A pressure amplitude that large would instantly break the bones in your ear.
As the air temperature rises, sound waves travel faster. For example, at 32 degrees Fahrenheit, sound waves travel through the air at 1,087 feet per second, or 742 miles per hour. However, at 100 degrees Fahrenheit, sound waves would travel at 1,163 feet per second, or 794 miles per hour
Blue whale communication has been measured up to 188 decibels, making it the loudest recorded sound from a living source. These underwater sounds have been detected 530 miles away.