How Big Ben's ' bong ' sound is created found

London : Scientists have used lasers to analyse how the Big Ben -- one of the UK's largest bells -- produces its harmonious sounds. The " bong " of Big Ben is produced when its 200kg hammer hits the side of the bell, setting off vibrations in the metal and causing the entire bell to pulsate. Officially known as the Great Bell, Big Ben is the largest of five bells that hang in the belfry of Elizabeth Tower at the Palace of Westminster. It is thicker than other bells of a similar size, weighing more and as a result having a higher pitch than expected , said Martin Cockrill from the University of Leicester, who led the study. Researchers said that although we perceived the chime of Big Ben to be a single sound, it was actually made up of a series of distinct frequencies. They used two lasers to scan Big Ben as it chimed at 9, 10, 11 and 12 o' clock. Scientists employed a technique called " laser Doppler vibrometry ", which involved creating a 3D computer model of Big Ben. Two lasers were then used to map the vibrations in the metal of the bell as it chimed. The researchers have produced animations showing the different vibration patterns of the bell. --- PTI ( The Times of India, Madurai, Friday, March 3, 2017 ) Courtesy : MPS