The Electric Network Frequency Based Method of Forensic Audio Analysis
https://doi.org/10.30764/1819-2785-2019-14-2-43-50
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.
About the Authors
A. A. Bessonov
Investigative Committee of the Russian Federation
Russian Federation
Russian Federation
Bessonov Aleksey Aleksandrovich – Doctor of Law, Associate Professor, Head of the Science & Research Department (Research Institute of Criminalistics) of the General Directorate of Criminalistics (Criminalistics Center)
Moscow 119311
A. G. Boyarov
Russian Federal Centre of Forensic Science of the Ministry of Justice of the Russian Federation
Russian Federation
Russian Federation
Boyarov Alexander Grigoryevich – Senior State Forensic Examiner of the Laboratory of Forensic Video and Audio Analysis
Moscow 109028
M. V. Stepanov
Investigative Committee of the Russian Federation
Russian Federation
Russian Federation
Stepanov Maksim Valer’evich – Head of the Audio Forensics Division of the Department of Organization of Expert Activities of the General Directorate of Criminalistics (Criminalistics Center)
Moscow 119311
References
1. Grigoras C. Digital Audio Recording Analysis: The Electric Network Frequency (ENF) Criterion. International Journal of Speech, Language and the Law. 2005. Vol. 12. No. 1. P. 63–76. https://doi.org/10.1558/sll.2005.12.1.63
2. Grigoras C., Cooper A.J., Micha£ek M. Forensic Speech and Audio Analysis Working Group Best Practice Guidelines for ENF Analysis in Forensic Authentication of Digital Evidence. Proceedings of the Forensic Speech and Audio Analysis Working Group. ENFSI FSAAWG Steering Committee on June 2nd, 2009. P. 1–10. http://enfsi.eu/wp-content/uploads/2016/09/forensic_speech_and_audio_analysis_wg_-_best_practice_guidelines_for_enf_analysis_in_forensic_authentication_of_digital_evidence_0.pdf
3. Grigoras C. Applications of ENF Criterion in Forensic Audio, Video, Computer and Telecommunication Analysis. Forensic Science International. 2007. Vol. 167. No. 2–3. P. 136–145. http://doi.org/10.1016/j.forsciint.2006.06.033
4. Korycki R. Methods of Time-Frequency Analysis in Authentication of Digital Audio Recordings. International Journal of Electronics and Telecommunications. 2010. Vol. 56. No. 3. P. 257–262. https://doi.org/10.2478/v10177-010-0033-0
5. Cooper A.J. An Automated Approach to the Electric Network Frequency (ENF) Criterion – Theory and Practice. International Journal of Speech Language and the Law. 2010. Vol. 16. No. 2. https://doi.org/10.1558/ijsll.v16i2.193
6. Cooper A.J. Further Considerations for the Analysis of ENF Data for Forensic Audio and Video Applications. International Journal of Speech Language and the Law. 2011. Vol. 18. No. 1. http://doi.org/10.1558/ijsll.v18i1.99
7. Ojowu O., Karlsson J., Li J., Liu Y. ENF Extraction From Digital Recordings Using Adaptive Techniques and Frequency Tracking. IEEE Transactions on Information Forensics and Security. 2012. Vol. 7. No. 4. P. 1330–1338. http://dx.doi.org/10.1109/tifs.2012.2197391
8. Huijbregtse M., Geradts Z.J.M.H. Using the ENF Criterion for Determining the Time of Recording of Short Digital Audio Recordings. In: Geradts Z.J.M.H., Franke K.Y., Veenman C.J. (eds.) Computational Forensics. International Workshop on Computational Forensics 2009. Lecture Notes in Computer Science. Vol. 5718. Springer, Berlin, Heidelberg. P. 116–124. http://doi.org/10.1007/978-3-642-03521-0_11
9. Saric Z., Zunic A., Zrnic T., Knezevic M., Despotovic D., Delic T. Improving Location of Recording Classification Using Electric Network Frequency (ENF) analysis. 2016 IEEE 14th International Symposium on Intelligent Systems and Informatics. (Subotica, Serbia, 29–31 August, 2016). P. 51–56. http://doi.org/10.1109/sisy.2016.7601517
10. Kajstura M., Trawinska A., Hebenstreit J. Application of the Electrical Network Frequency (ENF) Criterion. Forensic Science International. 2005. Vol. 155. No. 2–3. P. 165–171. http://doi.org/10.1016/j.forsciint.2004.11.015
Review
For citations:
Bessonov A.A., Boyarov A.G., Stepanov M.V. The Electric Network Frequency Based Method of Forensic Audio Analysis. Theory and Practice of Forensic Science. 2019;14(2):43-50. (In Russ.) https://doi.org/10.30764/1819-2785-2019-14-2-43-50
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