Forensic phonetics and speaker characteristics

The forensic task which phoneticians are most generally asked to perform is speaker identification. Usually the police want to know if a suspect is the speaker on an incriminating recording. Given the plasticity of the voice, and the variability of the relationship between speech and the ‘machine’ producing it (the speaker), phoneticians often shy away from identification and prefer to talk in terms of speaker comparison. Whatever the terminology, the holy grail of research in this area is a set of properties which are recoverable from the (often degraded) speech signal and which vary more between speakers than within the speech of one individual.