The Electric Network Frequency Based Method of Forensic Audio Analysis

Abstract

The article describes new possibilities for technical authentication of audio recordings and determination of circumstances in which they were made in the context of Russian forensic practice. The proposed method is based on comparing the frequency of the electric current in the grid reflected in the submitted audio evidence with reference electric network frequency (ENF) indicators, which are recorded on a regular basis using a specialized hardware and software suite. This method is known as the Electric Network Frequency (ENF) Criterion (developed by Romanian expert Catalin Grigoras in 2005) and has been used by forensic practitioners around the world since 2009. The paper discusses the substance of the method, its possibilities and limitations, and demonstrates its practical value in helping to establish whether an audio recording was tampered with, as well as the date and time it was made. The article is intended for experts as a summary of the method, and for investigators to familiarize themselves with the new possibilities of scientific methodology.