Forensic Speech Enhancement: Toward Reliable Handling of Poor-Quality Speech Recordings Used as Evidence in Criminal Trials

Abstract

This paper proposes an innovative interdisciplinary approach to evaluating the effectiveness of forensic speech enhancement (FSE). FSE faces unique challenges arising from a range of factors, from poor recording quality, highly variable conditions from case to case, and content uncertainty. Despite these difficulties, FSE is commonly admitted in court, and can significantly influence the outcome of criminal trials. Current FSE practices are hindered by unrealistic expectations from courts, which often assume that enhanced audio inherently clarifies content. In fact, FSE can have the undesired opposite effect, potentially resulting in unfair prejudice, when, for example, it increases the credibility of a misleading transcript. The proposed interdisciplinary project advocates for a better consideration of speech perception factors, particularly those related to transcription. It aims to bridge the gap between FSE and forensic transcription by promoting a combined approach to enhancing and accurately transcribing forensic audio. By developing a position statement on FSE capabilities, the project seeks to establish realistic standards and foster collaboration among researchers and practitioners. This effort aims to ensure reliable, accountable forensic audio evidence, aligning with forensic science standards and improving the effectiveness of the justice system.