Channel compensation for forensic speaker identification using inverse processing

Typically, speaker identification examination requires two audio recordings: a voice sample and a questionable recording. The questionable one is in most of the cases the intercepted or recorded phone call. As mobile phones became the most popular way of communication, the largest number of questionable recordings comes from GSM channels. They use special algorithms and devices to transmit the speech signal through the GSM channel, but these devices and algorithms change the original signal, thus the possibility of usage of such a recording for speaker identification becomes doubtful. In this paper we study how the GSM channel changes the formants position (frequencies) of the speech signal and how inverse filtering helps to compensate for the influence of the channel on speech signal and on forensic speaker identification performance.