Audio forensics behind the Iron Curtain: from raw sounds to expert testimony

Abstract

This essay investigates the construction of forensic audio expertise in the legal and security system of Communist Czechoslovakia and shows that the contested nature of speaker identification and sound-based objectivity contributed to the formulation of probabilistic claims in forensics. It explores the practices of the Department of Fonoscopy: a unique research laboratory of audio forensics that systematically examined the spectrographic, linguistic, and auditory means of sound analysis for the purpose of identifying unknown voices and environments in audio recordings. Bringing together the notions of “forensic cultures” and “sonic skills”, this article addresses the scientific, cultural, and political underpinning of the nascent field of audio expertise as well as the changing status of sound-based knowledge and forms of representation in forensics. In establishing fonoscopic expertise before the court and in the broader praxis of police investigation, the idea of vocal fingerprints and the use of sound visualisation technologies became instrumental. This essay pays special attention to the dynamics of the intricate process in which acoustic “raw material” (from anonymous calls, wiretapped phone lines, recorded conversations, or police interrogation rooms) was transformed into different kinds of legal and criminalistic evidence in the service of the totalitarian surveillance state.