NCJ Number
207476
Journal
Law Enforcement Technology Volume: 31 Issue: 9 Dated: September 2004 Pages: 96,98,101
Date Published
September 2004
Length
5 pages
Annotation
This article describes the professional capabilities and technology used by modern forensic audio analysts in identifying voices and other sounds pertinent to criminal investigations.
Abstract
Audio tapes secured as evidence in a case can be analyzed by the audio analyst beyond what is heard through a standard tape player. Through the use of noise-reduction and audio-enhancement software, sounds can be magnified and diminished in order to facilitate the identification of those that are of interest to the investigator. Voices on tape that have been intentionally distorted to prevent identification can be "cleaned-up" to remove the distortion and produce the normal voice of the speaker. Background noise on a tape can be magnified in order to determine characteristics of the location where a taped call originated. Audio analysts can use a spectrographic analysis of voice samples to determine whether two samples of distorted speech were made by the same voice (person) or different voices. In-person voice samples made by the analyst can also be compared to voice samples connected with a crime in order to determine whether a suspect was the speaker on a tape. This article presents a case study of the role and methods of an audio analyst in helping solve a staged fake kidnapping.