Analysis of Voice Changes in Anti Forensic Activities Case Study: Voice Changer with Telephone Effect

Abstract

Voice recordings can be changed in various ways, either intentionally or unintentionally, one of which is by using a voice changer. Reference voice recordings and suspect voice recordings will be more difficult to analyze if suspect voice recordings are changed using a voice changer application under certain effects such as telephone effect. Voice Changer can be one form of activity that can be carried out by anti-forensics, making it difficult for investigators to investigate if the voice recording is changed with telephone effect. This study has two types of recordings, namely the reference voice recording (unknown sample) and suspect voice recording (known sample) that has been changed using a voice changer application with telephone effect. Investigations were carried out based on data results extraction and analysis using pitch, formant, and spectrogram using the Analysis of variance (ANOVA) method and the likelihood ratio method. The results of this study indicate that the application of voice changer can be one form of activity that can be carried out by anti-forensics so that it can be difficult for investigators to conduct investigations on sound recording evidence. This research may help forensic communities, especially investigators to conduct investigations on sound recording.

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“…plies research results (First Author) mirip keluaran suara dari konversi audio, maka semakin jauh alfa (α) dan beta (β) ke suara asli maka konversi suara akan berbeda dengan suara aslinya [17]. Analisis yang dilakukan dapat diketahui bahwa suara Magic Call pada provider Telkomsel dan XL dengan rekaman suara asli memiliki fungsi yang berbeda.…”

Analysis of the Impact of Distortion on Sound Recordings as Anti Forensic Activities

“…The audio recorder also underwent a change from an analog phonograph recorder to a digital recorder that was not shaped like a recorder [7]. From several previous studies, voice manipulation has been carried out to change the identity of the original voice with various anti-forensic methods such as the use of a voice changer with a telephone effect conducted by A.B Baskoro [8] in 2020, the use of a voice changer with the effects of aliens, robots and zombies conducted by Rusydi Umar [9] in 2019, increasing 20% audio speed conducted by Yasep Azzery [10] in 2020 and the use of MDCT audio conducted by Tao B [11] in 2020.…”

“…In a study conducted by A.B Baskoro [8], the voice changer method with telephone effects was able to manipulate the authenticity of the voice with an average value of 63.4% and 61.4%, respectively. In a study conducted by Rusydi Umar [9] using a voice changer method with robotic, alien and zombie effects as well as a study conducted by Tao B [11] using the MDCT audio method to manipulate the authenticity of the voice.…”