Forensic Speaker Identification explains what FSI involves, and clarifies the problems of inferring identity from speech under the less than ideal conditions typical in forensics. The text discusses the complexities of voice sample comparison, the probabilistic nature of the technique, the difficulties introduced by differential variation within and between voices, and the expertise required in linguistics and acoustics. Written for forensic scientists, the legal profession and law enforcement officers, this book is also accessible to those with no previous knowledge of FSI and can be used as a base for teaching tertiary level courses in aspects of phonetics.