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CYFOR Investigator, Michelle Bowman, who conducted the audio and video analysis of the video footage, explains what is involved in this type of analysis and ways to determine if a video has been altered.
“There are two parts to the process of audio and video analysis in which we look for discrepancies. These are listening and watching.”
“During the listening stage of analysis, you would expect to hear a continual flow of sound, which is the same with any ambient noise in the background. When audio clips are joined together you would normally hear an audible click indicating discrepancy in the video.
“We can also analyse the letter sounds. This was done as part of the Jeremy Clarkson investigation to determine what had been said.”
Michelle continues, “For example, the sound for the letter ‘g’ is a deep sound made towards the back of the mouth without the lips touching. This was the situation in the Jeremy Clarkson case, which enabled us to determine what had been said.”
“During the watching stage of analysis, we use a Spectrum Analyser. This is specialist equipment that allows us to split sounds into frequency components, in order for us to see changes in electrical signals. This enables us to see inconsistencies in the sound and background noise. If there are two different recordings joined together, for example, we can identify discrepancies indicated by a spike in the wave.
“Regarding the footage of BBC presenter Jeremy Clarkson, this was examined via this method, but there was found to be no evidence of tampering.”
“We are usually given poor quality CCTV, from when it was a dark night for example. Through the application of specialist methods and equipment, we can sharpen the footage and bring up the colours. This makes it easier for us to identify inconsistencies in the footage. We get a lot of CCTV footage from the police, and have helped them to build many solid cases over the years.”
Michelle commented on a recent case, “We recently worked with the police to investigate footage of the murder of 15-year-old Sean McHugh in Liverpool. He was stabbed in the leg in a laundrette with a sword walking stick. We were asked by the defence to carry out analysis on the visibility of weapons, as one of the accused had denied knowledge of their existence. Our analysis and findings have played a vital role in the investigation.”
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