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Newsletters > July

AUDIO FORENSICS
Or Digging through the Trash for the Treasure


 
He is generally asked to answer whether recorded events are indeed gunfire, to verify the type of weapon, the location with respect to the microphone(s), and the timing and number of shots.  The sources of these recordings are quite varied, and can include dashcams, bodycams, taser-cams, dispatch center recordings, security cameras with audio, and commercial gunshot detection systems.  These recordings can be subject to multiple distortions, including but not limited to background noise, overlapping gunshots, inadequate signal-noise, codec distortion, time variance distortion caused by moving sources or recording devices, and environmental context effects of reflection and absorption.  These confounding effects can cause experts to achieve different conclusions, Dr. Begault showing a graph noting the discrepancies in the timing of gunshots found by four different forensic audiologists.
 
 
After discussing the topic in greater depth, Dr. Begault segued into an overview of forensic musicology, breaking it into compositional, recording, and production analyses.  Compositional analysis involves copyright infringement irrespective of the recording media, and requires expertise in music theory and compositional analysis.  This type of infringement is difficult to prove, and requires that the defendant had prior access to a song, that the song under examination has substantial similarity in melody, rhythm and structure to the prior work, and that the elements themselves are copyrightable.  In the case of Gaye vs. Thicke, two experts reached opposite conclusions, Judith Finnell claiming that the songs were “the same,” where Sandy Wilbur asserted that they were not “meaningfully similar,” and were “really different songs.”
 
 
Dr. Begault concluded his discussion by discussing the issues of reliability of the evidence evinced by forensic audiologist.  He noted that at the current time, it’s very difficult to assign measures of the accuracy of the inferences, nor even a measurement of the uncertainty of the judgments made by forensic audiologists.  Replication of results is difficult, statistical analysis can rarely be performed, contexts vary greatly, all of which make standardization and consistent results challenging.
 
 
The Audio Engineering Society, Los Angeles Section wishes to thank Dr. Durand Bergault and the Audio Forensics Center of San Francisco for his fascinating and stimulating talk.
 

......Recap by John Svetlik

 

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