Voice-altering technology and crime
Voice-altering technology involves the artificial manipulation of voice pitches through electronic means, enabling the scrambling of voice communications to obscure identities and content. This technology plays a significant role in various contexts, particularly in criminal investigations, where it is used to hide the identities of speakers involved in activities such as wiretapping, kidnapping, and terrorism. In these scenarios, altered voices must often be analyzed by forensic scientists to confirm the identity of the individuals speaking. Additionally, this technology is utilized by military and security services to protect sensitive communications from eavesdroppers through speech encryption, which renders conversations unintelligible to outsiders.
Voice alteration is also leveraged by individuals who impersonate others to gain unauthorized access to protected information or locations, exploiting systems that rely on voice recognition. Commercially available voice-changing devices vary in sophistication, from portable units to professional-grade equipment capable of more natural-sounding alterations. While these devices can modify voice pitch, they do not affect speech patterns or accents, which forensic linguists can analyze to identify speakers. Furthermore, artificial intelligence can aid in forensic analysis by matching altered voice samples to databases and tracing calls in criminal investigations. Ultimately, voice-altering technology presents both opportunities for protection and challenges in crime prevention and detection.
On this Page
Subject Terms
Voice-altering technology and crime
DEFINITION: Changing of the pitches of voices artificially through computer or other electronic manipulation or the electronic scrambling of voice communications so that they are unintelligible to eavesdroppers.
SIGNIFICANCE: Most common uses of voice alteration represent attempts to hide the identities of the speakers. Voice-altering technology comes to the attention of forensic scientists in situations such as criminal wiretap, kidnap, and terrorist cases in which altered voices are recorded and the persons speaking must be positively identified. The scrambling of voice communications, another kind of electronic voice alteration, is used by military and security services to prevent outsiders from accessing the contents of messages.
Electronic voice alteration is most often done to disguise the identities of speakers involved in criminal activities such as stalking or threatening, when the speakers anticipate that recordings might be made of their voices or their communications might be intercepted by wiretaps. Voice alteration is also sometimes used by persons who imitate the voices of others to gain access to protected information or places. For example, some computer files and physical locations are protected by voice recognition systems that may be fooled by electronically altered voices. Voice alteration may be used in the impersonation of persons over the telephone to acquire information to which those persons have restricted access. Electronic voice manipulation is also sometimes used to protect the identities of witnesses or victims of crimes who agree to speak about their experiences publicly, such as on radio or television programs.
Several types of voice-changing devices are widely available commercially. One is a portable device that can be held over the mouthpiece of a telephone. More sophisticated devices can be connected to landline telephones. These voice-changing devices alter the pitch of the speaker’s voice, making it sound higher or lower. They produce the most natural and human-sounding voices when the pitch is adjusted by no more than two octaves. The greater the change, the more artificial, electronic, or cartoonish the voice sounds. Professional-quality equipment is required to convert the low-pitched bass voice of a man into a natural-sounding woman’s speaking voice.
Forensic scientists who specialize in the detection and analysis of altered voices are called forensic linguists or forensic stylists. Voice-altering equipment cannot change speakers’ accents or speech patterns, and forensic linguists are able to use these factors, along with word choice, grammar, and sentence complexity, to identify the persons behind electronically altered voices.
Artificial intelligence (AI) can aid forensic scientists in several ways. It may be used to match voice samples with existing records in a database and identify a suspect or victim. AI can also assist in tracing calls. Police officers and detectives often receive recorded phone calls related to criminal cases. AI can analyze the voice and speech patterns to potentially identify the caller.
A different type of electronic voice alteration is used in speech encryption. Speech encryption—the scrambling or compressing of voices—is done for security purposes, to protect the contents of voice transmissions from eavesdroppers. An electronically compressed or digitally scrambled conversation sounds like nonsense to anyone listening. The intended recipient, however, has the hardware and software needed to decode the message, making it intelligible. This type of electronic voice alteration is used most extensively by the military and security services and is the basis for their secure telephone systems.
Bibliography
Diffie, Whitfield, and Susan Landau. Privacy on the Line: The Politics of Wiretapping and Encryption. Cambridge, Mass.: MIT Press, 2007. "Harnessing the AI Power in Forensic Voice and Speech Analysis." Forensic Science Blog, July 3, 2023, forensicscienceacademy.org/blog/f/harnessing-the-ai-power-in-forensic-voice-and-speech-analysis. Accessed 14 Aug. 2024.
"Hollien, Harry. Forensic Voice Identification. San Diego, Calif.: Academic Press, 2002.
Kalat, David. "Nervous System: From a Cry in the Dark to the Forensic Voiceprint." Berkeley Research Group (BRG), 4 May 2022, www.thinkbrg.com/insights/publications/kalat-ns-forensic-voiceprint/. Accessed 14 Aug. 2024.
Tanner, Dennis C. Medical-Legal and Forensic Aspects of Communication Disorders, Voice Prints, and Speaker Profiling. Tucson, Ariz.: Lawyers & Judges Publishing, 2007.
Tanner, Dennis C., and Matthew E. Tanner. Forensic Aspects of Speech Patterns: Voice Prints, Speaker Profiling, Lie and Intoxication Detection. Tucson, Ariz.: Lawyers & Judges Publishing, 2004.