London – Scientists have revealed what causes the harmonious sound of the Big Ben through a study involving lasers.
Researchers at University of Leicester revealed that the “bong” of Big Ben is produced when its huge 200kg hammer hits the side of the bell, setting off vibrations in the metal and causing the entire bell to pulsate, researchers said.
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.
According to scientists although the chime of Big Ben is perceived to be a single sound, it is actually made up of a series of distinct frequencies. Using two lasers, scientists scanned 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. Using two Scanning Laser Doppler Vibrometers, the team was able to characterise Big Ben without touching it providing high-density vibration measurements without any loss of accuracy or precision.
The findings of the mapping project will be revealed during a BBC documentary entitled ‘Sound Waves: The Symphony of Physics’, which will be broadcast at 9:00PM on Thursday 2 March on BBC4 and is hosted by Dr Helen Czerski.