Tampering Detection in Digital Audio Recordings
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Solution Overview
Problem
Current methods for forensic authentication of digital audio recordings are unreliable in detecting tampering and identifying the source location, as they fail to distinguish between genuine power grid disturbances and tampering, and are limited to identifying the power grid interconnection rather than the specific location within a city.
Innovation Solution
The method involves extracting frequency and phase angle sequences from digital audio recordings using short-time Fourier transforms, matching them against reference databases, and extracting noise sequences to improve tampering detection and location identification, utilizing a network of sensors and databases to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ENF sequence extraction algorithms are used to detect tampering, then tampering detection capability is improved, but reliability deteriorates due to false positives from power grid disturbances
Solution Approach 1:
The patent segments the phase angle sequence into multiple smaller segments and analyzes each segment independently. This allows the system to identify and exclude segments affected by power grid disturbances while retaining segments that contain genuine tampering evidence, thereby improving reliability without sacrificing measurement precision.
Solution Approach 2:
The patent introduces an intermediary analysis layer that compares phase angle sequences from multiple segments against reference databases and applies consistency checks. This intermediary process filters out false positives caused by power grid disturbances while preserving genuine tampering detections, resolving the contradiction between reliability and precision.
2Measurement precision
If ENF sequence matching is used to identify location, then location identification capability is improved, but precision deteriorates because only interconnection level (not city or state level) can be identified
Solution Approach 1:
The patent transitions from a single-dimension approach (matching ENF sequences only against interconnection-level references) to a multi-dimensional approach by analyzing phase angle sequences across multiple segments and comparing them against hierarchical reference databases that include city and state-level granularity. This dimensional expansion enables precise location identification while preserving detailed location information.
Data Source
AI summary
Systems and methods for detecting a tampering and identifying a location of a digital recording are provided. A frequency sequence and a phase angle sequence may be extracted from the digital recording. A portion of the frequency sequence may be matched to one of a plurality of reference frequency sequences, and a portion of the phase angle sequence may be matched to one of a plurality of reference phase angle sequences. Tampering of the digital recording may be detected when the frequency and phase sequences differ from the matched reference sequences. Moreover, a noise sequence may be extracted from the extracted frequency sequence. A location of the digital recording may be identified by matching the noise sequence to one of a plurality of noise sequences of the plurality of reference frequency sequences.