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Digital audio recording analysis: the Electric Network Frequency (ENF) Criterion

Domenii publicaţii > Stiinte ingineresti + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: Catalin Grigoras

Editorial: Equinox, International Journal of Speech Language and the Law, 12(1), p.14, 2005.


This article reports on the Electric Network Frequency Criterion as a
means of assessing the integrity of digital audio evidence. A brief description is given of
phenomena that determine ENF variations. In most situations, to reach a non-authenticity
opinion, the visual inspection of spectrograms and comparison with an ENF
database are enough. A more detailed investigation, in the time domain, requires short
time windows measurements and analyses. The stability of the ENF over geographical
distances has been established by comparison of synchronized recordings made at different
locations on the same network. A real case is presented, in which the ENF
Criterion was used to investigate an audio file created with a secret surveillance system.
By applying the ENF Criterion in forensic audio analysis, one can determine whether
and where a digital recording has been edited, establish whether it was made at the time
claimed, and identify the time and date of the registering operation.

Cuvinte cheie: forensic audio