An Interrogation Speech Manipulation Detection Method Using Speech Fingerprinting and Watermarking

Abstract

We proposed a manipulation detection method for interrogation speech. We used a robust fingerprinting method optimized for speech since our intended target is interrogation speech recorded during a police investigation. The fingerprint uses line spectral pairs (LSP) to measure the spectral envelope of the speech, and is coarsely quantized so that the fingerprint will not be altered by small degradation in the signal, but will be altered enough by malicious modifications to the speech content. This fingerprint is embedded in the speech signal using conventional spread-spectrum watermarks. To detect manipulation, the watermarked fingerprint is detected, and compared to the fingerprint extracted from the speech itself. If the fingerprints match within the predetermined tolerance, it can be authenticated to be unaltered. Otherwise, manipulation should be suspected.

We conducted manipulation detection on a frame by frame basis, and confirmed that we can correctly detect manipulation with noisy and reverberant speech in almost all of the substituted frames.