Engineers measure Big Ben’s bong

Posted by ap507 at Mar 08, 2017 09:15 AM |
Engineers contribute to major BBC documentary on sound to reveal why Big Ben produces distinct tone and feature on BBC's Daily Politics show
Engineers measure Big Ben’s bong

The Elizabeth Tower containing Big Ben; Credit: Carl Vivian / University of Leicester

A team from our Department of Engineering has, for the first time ever, vibration-mapped the famous London bell Big Ben in order to reveal why it produces its distinct harmonious tone.

The group, from the Advanced Structural Dynamics Evaluation Centre (ASDEC), measured four of Big Ben’s chimes, taking place at 9AM, 10AM, 11AM and 12 noon.

The ASDEC team used a measurement technique called ‘laser Doppler vibrometry’. This involved creating a 3D computer model of Big Ben and then using lasers to map the vibrations in the metal of the bell as it chimed.

ASDEC, working with the BBC, measured the structural dynamics of Big Ben in an unprecedented level of detail after being given exclusive access to the iconic structure.

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 was broadcast at 9:00PM on Thursday 2 March on BBC4 and was hosted by Dr Helen Czerski.

Martin Cockrill, a Technical Specialist from the Department of Engineering, who leads ASDEC's measurement team and appears in the documentary, said: “Aside from the technical aspects one of the most challenging parts of the job was carrying all of our equipment up the 334 steps of the spiral staircase to the belfry. Then to get everything set up before the first chime, we were literally working against the clock.

“Many of the vibrations in the metal of Big Ben are too tiny to be seen by the naked eye. But this is what we were able to map using the lasers and not just one or two points on the surface; we were able to get over 500 measurements across the surface which just wouldn’t have been possible with previous technologies.”

Martin Cockrill and Max Chowanietz led the team from a technical point of view undertaking the measurements with two other members of the team, Chris Howe and Amy Stubbs.

Max is a graduate engineer with ASDEC who completed a General Engineering Degree at the University of Leicester in 2014 and has since followed his passion.

Max said: “It was a privilege to be part of such a unique project, especially so early in my career.”

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