Audio analysis
Analysis of the soundtracks of available footage – witness videos, CCTV recordings – to date events, establish their sequence, and reconstruct what was said or heard at the scene.
Sound carries information that the image does not show: the number and spacing of detonations, the distance between the source and the microphone, the order in which words were exchanged. Analysing it lets us synchronise videos filmed from different vantage points, and build a chronology accurate to a fraction of a second where the images alone remain silent.
Index has used this method notably on the killing of Nahel Merzouk, with the Earshot collective, and on the arrest in L’Île-Saint-Denis, whose recordings were published in full.