On Tuesday, June 27, 2017 at 8:00 p.m., the Audio Engineering Society, Los Angeles Section heard a presentation from distinguished guest Durand Begault on the topic of Forensic Analysis and Audio Engineering:Digging through trash for treasure.Dr. Begault traveled to Los Angeles meeting from the Audio Forensic Center of Charles M. Salter Associates in San Francisco.He covered a range of topics in audio forensics, including the authentication and enhancement of voice recordings, unique considerations concerning cellular telephone voicemail, the reliability of gunshot analyses, comparisons of music in copyright infringement cases, and finally, how well do current audio forensic practices conform to the overall standards of science.
Dr. Begault began by describing audio forensics as the “‘Scientific’ analysis of audio and acoustics pertaining to a legal matter.”One of the most common tasks that he is asked to undertake is the enhancement of noisy recordings, to make recorded speech more intelligible, enabling transcription, and in some cases to make an event detectable.This naturally requires that there is sufficient signal in the noise to begin with, which is frequently not the case.The process of enhancement requires a great deal of judgment, from how to prevent the addition of new audio artifacts, as well as how to control one’s own biases.He notes that one must be willing to label parts of a recording as unintelligible if need be, and that one must resist loosening appropriate standards in order to please a client.Furthermore, one must achieve a standard of clarity and intelligibility that would be available to a jury, not just to a pair of “golden ears.”He explains that as an audio forensics consultant, his determinations are technical and not evidential - a judge determines whether the evidence can be admitted into a case, but he provides technical expertise on matters such as provenance (where did it come from?) and continuity (has it been edited?).The tools a forensic audiologist uses are critical listening, waveform analysis (particularly with respect to