Expert Witness Blog
In Acoustic Signal Analysis For Forensic Applications, acoustics expert witnesses Durand Begault and Christopher Peltier write:
Acoustical analysis of audio signals is important in many legal contexts for determining the authenticity, originality, and continuity of recorded media; determining the circumstances of events in question that may have been recorded; for determining the audibility of signals; and for identification or elimination of talkers as a match to an unknown exemplar.
Recorded media are analyzed in forensic applications using both familiar techniques (waveform and spectral analyses) and more novel methods (e.g., ferro fluid development of media; specialized tape heads with nonstandard reproduction characteristics; crystal microscopy; detection and matching to power grid frequencies). Audibility analyses frequently require careful reconstructive field measurements and criteria in excess of normally accepted standards. Voice identification-elimination protocols must account for examiner bias and exemplar quality and can be described using a receiver operator curve (ROC) model.