where does the sound of a burp come from
Burping Burping is generally caused by swallowing air when eating or drinking and subsequently expelling it, so in this case the expelled gas is mainly a mixture of nitrogen and oxygen. Burps can also be caused by drinking carbonated beverages, such as beer, soft drinks, energy drinks, and wine in which case the expelled gas is primarily carbon dioxide from the drink itself. Common diabetes drugs metformin[1] and Byetta[2] can cause burping, especially at higher doses. This often resolves in a few weeks. Burping combined with other symptoms such as dyspepsia, nausea and heartburn may be a sign of an ulcer or hiatal hernia, and should be reviewed by a physician.[3] Other causes of burping include: food allergy, gallbladder problems, acid reflux disease, H. pylori, and gastritis.
Sonic boom When an aircraft passes through the air it creates a series of pressure waves in front of the aircraft and behind it, similar to the bow and stern waves created by a boat. These waves travel at the speed of sound and, as the speed of the object increases, the waves are forced together, or compressed, because they cannot get out of each other's way quickly enough. Eventually they merge into a single shock wave, which travels at the speed of sound, a critical speed known as Mach 1, and is approximately 1,235 km/h (767 mph) at sea level and 20 °C (68 °F).