Among the many things that make us who we are, our voice is a major factor. The ability to use voice to form words and hold a conversation is something only humans are blessed with. But speech can be tampered and misused to form malicious messages. When this happens, the individuality of the voice and identity of the person is lost. The job of a forensic personnel is to reestablish the authenticity of the individual. This is where the examination of tampered voice comes in. By focusing on the minute differences between original and tampered audio exhibits, a lot of evidence for a culpable crime can be collected. This chapter aims to serve as a basic guideline on how to approach the examination of such tampered voice samples.

This chapter will start by explaining how speech is produced and how hormones affect the pitch of voice. Then it will explore the ways in which speech can be tampered. Further the procedure for tape authentication and speaker identification in Forensic Science Laboratories will be discussed in detail in this chapter. During analysis of speech, various spectrographic tools are used that employ waveforms for in-depth signal processing. This chapter will explain the working of few such tools like Goldwave, Computerised Speech Lab, etc. Lastly, case studies in India and worldwide that have used tampered speech as evidence will be studied from a student’s point of view.