Forensic Authenticity Analyses of Tape-Recorded Evidence

by Namrita Raje

Whether you are the proponent or opponent of tape-recorded evidence, expert determination of a recording’s authenticity may at least affect the weight of the evidence, if not make a difference in its admissibility.

As unbiased forensic tape examiners, we can objectively, thoroughly and properly authenticate both the content and magnetic patterns of the recording(s) at issue. The most thorough forensic analysis is of the original tape(s) and the original recorder. Thorough Forensic Authenticity Analysis of a recording ensures that evidence of any type of tampering will be exposed, and any signs suggestive of falsification will be appropriately analyzed and explained. As it is observed that the portion that is manipulated shows some noise or distortions in the process of analysis through voice spectrography.

Discourse or Linguistic Analysis of Speech

Discourse or linguistic analysis of speech is the scientific analysis of a dialogue which, when presented by a forensic linguist, may be able to determine how and why one's statements do not convey the significance that someone else attaches to them.

Effective communication between two or more people requires spoken information exchange. Such exchange must be linguistically congruous, i.e., it must be logically ordered to give each conversant a meaningful chance to raise topics and respond accordingly. However, one does not always reveal the meaning of his/her speech through explicit words alone. Non-speech expressions -- equally important as the spoken words themselves – may complement the conversation, including intonation patterns, turn-taking, back-channeling, word choice, rhetorical style, interruptions, repetitions, and even politeness.

The above situation may be more confusing when a non-conversant (e.g., fact finder) inaccurately construes the intent of the conversants’ conversations. A non-conversant usually has a limited understanding of a taped conversation that is complex in nature. Words, phrases, intentions and motives can be construed in many different ways, but usually from the context of non-conversant’s experiences and perceptions at the time of the utterances. To fully understand the actual context of the conversation rather than construing the conversation from the non-conversant's perspective and experiences, We need to research the speakers, the speech content, the purposes of the conversation, the manner of the utterances, etc. By objectively explaining the structure of the conversation, discourse or linguistic analyses may provide a method for third parties to properly evaluate the recorded conversation.

Get Out of Jail Free? A fellow was in jail for car theft with just three months remaining to serve. He was impatient to get out, so he called the local F.B.I. office posing as an out of town agent requesting to use him as an informant on the street. He asked the local agent to get him out of jail as soon as he could. The wheels started to turn, and plans were being made to release him early when, one alert agent asked him whether he had worked with any agents in the local office recently. He named an agent who had arrested him years ago and said that he had talked to him a few weeks earlier. Unfortunately, for him, the agent had passed away a year ago. When the agents came to release him, he was re-arrested and given two additional years in jail. The telephone calls from jail were recorded on a multi-channel machine. We downloaded the conversations at the jail, and enhanced them for confirmation that the inmate was in fact, the caller. Go directly (back) to jail.

The Teacher and The Killer

Karen Weinstein, a teacher and mother, in New Jersey, was studying to become an assistant principal. She used a small micro-cassette recorder to record her notes in preparation for her assistant principal exam. One night she made the mistake of stopping at a strip mall for a sandwich. A young man carjacked her and drove off with her in the car, threatening to kill her as he drove to a deserted area. He told her that he wanted the car, and she told him to take it while pleading for him not to hurt her. Somehow, despite being terrified, she managed to record a good amount of the conversation using her microcassette recorder. Tragically, her body was found some time later, along with the microcassette. After a preliminary examination by the State forensic lab, the tape was sent to me for further study. After careful examination and digital enhancement we were able to recover an additional 22 minutes of conversation, including information useful in making a positive identification of the killer. He later pleaded guilty, saying that he wanted the car for his birthday.

The Dumpster Baby

Two college sweethearts from different schools found themselves in serious trouble when the girlfriend discovered that she was about to have a baby. She called and left a message on her boyfriend’s answering machine, hysterical, saying that she hoped that her worst nightmare wasn’t coming true and to get over there right away. The message was very noisy and distorted. The baby’s lifeless body was later found in a dumpster. The tape was sent to the state lab as well as to the F.B.I. lab. Aftr careful enhancement we were able to recover additional information. A plea agreement was ultimately agreed to, by all parties.

The Bikers in Jersey

A number of bikers placed ads in newspapers advertising for “models” to lure girls to their “party” house for sex. The girls were fed alcohol and qualuudes to put them in a semi-conscious state. They were then gang-raped. The bikers, in their infinite wisdom, videotaped the sessions, and in several cases actually attempted to extort money from some of the girls by threatening to show the tapes to the girls’ families if they didn’t empty their bank accounts and pay them. One girl’s recollection of the vents led to a search warrant , in which the self-made evidence videocassettes were seized. The prosecutor’s office engaged me to enhance the audio and prepare discovery copies for trial. Ultimately, all defendants pleaded guilty and none of the girls had to be subjected to a painful trial. The bikers were sent to Rahway state prison for long prison terms.

Turning Donald Duck into a Judge

New York Chief Judge Sol Wachtler was having an affair. When the lady involved ended the affair, the Judge, wanting to continue, kept calling his lady friend. Then one day she received a threatening call from someone using a voice changer. The voice was distorted and clearly had been changed using an electronic device.
Federal prosecutors gave us the tape and asked whether we could unscramble the conversation. Using a computer as well as several consumer speech changers we were able to restore the voice along with a stable hum recorded at the time of the conversation. This hum signal served as a reference to tell me that the scrambling had been successfully reversed.The voice on the phone was that of the judge.

Yachts and Jets in Jail

Irwin Feiner was a con man. His modus operandi was to purchase yachts and jets and overfinance them by getting them appraised for more than their actual value. He would then take a half million dollars from the loan proceeds and hide it. The jet or yacht would be leased for a while and then he would default on the loan payments. And then he would go to the next bank and start all over again. The amazing thing about this scheme was that he continued it while in jail. He called bank officers and explained the echoing of the prison saying he was at his health club. All telephone calls at the prison were recorded on a 40-channel tape but there was no way to determine which of the thousands of inmate phone calls were from Feiner. Each large reel had the capacity of recording 40 telephone lines for 24 hours.

Our job was to design a system to automatically detect all of the touch tones of the phone calls, download them into a computer, compare them with the known 105 telephone numbers Feiner was known to call, and output a printout of the relevant phone call dates, times and channels for review and downloading of the pertinent conversations.ultimately Feiner was convicted of fraud while in jail.

During the course of multimillion dollar brokerage transactions, conversations are routinely recorded not for “instructional purposes” as the pre-recorded messages would have you believe, but rather for insurance for the recording party in the event that there is a difference of opinion as to recollection of details after the fact.
We were able to retrieve about 95% of this “almost lost” conversation. Its like true “audio archeology”.


We’ve tried to give you a glimpse into the life of a tape expert, illustrating the different types of cases that they deal with on a daily basis. In addition, there are lectures to law enforcement in the use of tapes during investigations, and an ongoing dialogue with surveillance and recorder manufacturers so as to insure that the tapes recorded are valid legally as bona fide evidence in courts of law, along with supporting expert testimony.

Author:- For further queries on this topic you can contact me on my id :-

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May 07, 2008
Fascinating Article
by: David

Hi Namrita

Many thanks for submitting another excellent article, it's very much appreciated.

Kind regards

David & Iain

If you haven't read Namrita's article on Forensic Speaker Identification & Speaker Profiling you can do so by Clicking Here

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