You searched for: “voiceprints
voiceprint (s) (noun), voiceprints (pl)
1. When recording a person’s voice electronically, and representing it in a graphic form, a person can be biometrically identified: It is interesting that no two people in the world have the same voiceprint, just as no two people have the same fingerprints.
2. A representation in a graph form of the frequencies that make up someone's voice: In voiceprint, usually the rate of occurrence of a person’s speech is plotted on the vertical and the time is located on the horizontal axis.

The voiceprint the police used to identify the man who had spoken on the victim’s answering machine was very helpful in solving the crime that was committed on the weekend.