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Archive for the ‘Audio Forensic Expert’ Category

JFK Assassination: Fully restored Air Force One recordings from November 22, 1963

Tuesday, November 19th, 2013

John F Kennedy At the end of this blog post is a fully restored digital audio file available for listening and downloading of the government conversation that occurred at the time of the assassination of President John F. Kennedy. The Announcer at the beginning of the recording  is the poorest quality of the entire 2:01:59.

This is a combination merged from two copies that were in existence. The first copy was released by the government and referred to as the ‘LBJ tapes’ in the early 1970’s. Another longer copy surfaced in a Philadelphia private auction in 2011. This longer copy was found in the belongings of the late General Clifton. Thanks to Bill Kelly, a veteran JFK researcher, Primeau Forensics has combined the contents of both recordings and fully restored them.

In this enhanced recording, you will hear conversations from Air Force One over the Pacific Ocean as they abort a trip to Japan and turn around, mid-air, to return to the mainland after learning about the assassination of the President of the United States. These recorded conversations between Ground Command, the White House and Air Force One include code names such as ‘Duplex,’ ‘Digest,’ ‘Volunteer,’ ‘Liberty,’ ‘Witness,’ ‘Crown,’ ‘Baker,’ ‘Watchman,’ and ‘Tiger.’

During the call they make arrangements to transport John F. Kennedy’s body, his widow, President Johnson and the other 40 people safely back to Washington DC. The carefully coordinated and strategically executed planning is heard in this recording. Decisions about media coordination on the ground at the White House, the post-mortem autopsy to be performed by law and President Johnson’s conversation with JFK’s mother, Rose Kennedy can also be heard.

It may take a while to get your ears acclimated to this early, mobile technology. Primeau Forensics has carefully removed unnecessary radio static and squeals to accommodate better listening. It is recommended that you use a combination of speakers and headphones to best listen to these recordings.

Listen to the updated Clarified Audio Track HERE:

[audio:http://www.primeauproductions.org/primeauforensics/JFK Airforce One Primeau Forensics .mp3|titles=JFK AIR FORCE 1 CLARIFIED AUDIO UPDATE]

Download Recordings Here!

Download Transcript Here!

Air Force One Audio Restoration/Enhancement Process

Friday, November 15th, 2013

Air Force OneA lot of people have been asking how I restored the Air Force One radio transmissions from November 22 1963, right after JFK was shot. Below I have outlined my process with brief explanations about each.

I used a software program from Adobe CS 6 ‘Audition’ for this entire process.

I identified the points in each version of the tape recordings, the LBJ version and the General Clifton version, for edit points before altering the recordings for enhancement.

I began the restoration process by sampling the tape hiss present on the entire recording and reducing with Adobe noise reduction. Next I went section by section and reduced the radio transmission noise which varied from conversation to conversation.

Then I applied equalization and compression filtering to help bring out the conversations. This was also done section by section since each conversation varied in speaking frequencies.  Adobe CS6 has a great tool, the FFT equalization which is very easy to use.

Audio restoration and enhancement is a process. I refer to it as peeling an onion; one layer at a time. If something does not sound right, I go back a step and try a different process. That’s the beauty of digital audio restoration and enhancement.

I am still working on the restoration as time permits and will update the videos posted here. I am hearing more and more of the conversations using critical listening and additional enhancement. Considering how primitive the technology was back then I am very impressed with the sound quality of these recordings. By the way, the General Clifton version is much better sounding and longer then the LBJ version.

Read about how this all started, and you can watch the story on “The Lead” with Jake Tapper on CNN below.

Primeau Forensics Restored Air Force One Recordings from John F. Kennedy Assassination

Tuesday, October 8th, 2013




Passing the Torch-An International Symposium on the 50th Anniversary of the Assassination of President John F. Kennedy will be happening October 17-19 2013 in Pittsburgh. http://www.duq.edu/events/jfk

A while back, Bill Kelly contacted Primeau Forensics and asked Audio Forensic Expert Ed Primeau to assemble and restore the original Air Force One radio transmissions that were recorded the day JFK was assassinated 50 years ago.

According to Primeau, ‘the quality of technology back then was very poor which weighs heavy on understanding the dialogue of the radio transmissions even after restoration’. Then Primeau had an idea, to have Partner Company Primeau Productions create a video which displays the wording on the bottom of the screen displaying the dialogue from the radio transmissions as they occurred.

Primeau sought some authentic footage from a private jet cockpit via a pilot who is a friend of Primeau Productions so the background footage adds an interesting background to the closed caption type text.

For more information on the conference contact:

Deborah G. Jozwiak

320 Fisher Hall
600 Forbes Avenue
Pittsburgh, PA 15282
Email: wechtinstitute@duq.edu
Phone: 412-396-1330
Fax: 412-396-1331

Voice Identification and Critical Listening

Wednesday, September 18th, 2013

critical listening Imagine for a moment that you’re sitting at home after a long day at work, enjoying some time in your living room, watching TV or the like.  All of a sudden, you hear the door open behind you.  You sit and wonder who could have walked in, until the anonymous person speaks.  The second you hear their voice, you recognize and register immediately who has entered the room. The same scenario can happen all day at work as well. You learn to recognize your co-workers voices after hearing them all day for several months, even years.

As these examples show, we recognize and interpret characteristics of voices very quickly. Why is this? Vocal characteristics are very distinct amongst all people regardless of race, gender, or ethnic background. If you spend a decent amount of time around someone, you become used to the vocal characteristics they express and can immediately correlate those characteristics with the identity of who is speaking to you.

Vocal Identification in audio forensics relies on the ability to recognize these characteristics in any unknown human voice. In the examples above, the repetition of exposure to those vocal characteristics make you respond without even thinking twice about who could be behind you.  The difference in regards to audio forensics is that a forensic expert doesn’t always know anything about the voice in question. This requires the forensic expert to rely on their ‘critical listening skills.’

So, how is this done? What specific characteristics are forensic experts actually looking for?  They look for the types of speaking characteristics that could be relevant and specific in identifying a person’s voice.  Everyone has very distinct features to their voices, regardless of how slight or severe they might be.  When compiling information for voice identification, the forensic expert must listen over and over to the unknown voice with pen and paper taking scrupulous notes of all speech characteristics. They focus specifically on things such as inflection, pronunciation of certain words, any form of an accent, stutters and lisps, amongst other variables. Make careful and precise notes about all of these variables.  They try to be as SPECIFIC as possible.  The forensic expert will then create a voice profile for this person.

If by chance the forensic expert has access to the suspect thought to be the unknown voice, this puts them at more of an advantage.  The goal then is to create an exemplar of that person saying the same message in question with the same delivery heard in the recording. This is called an ‘exact exemplar.’ They will review and compare notes from both the original recording and the exemplar itself. An exemplar gives you a more neutral quality, and isn’t biased by background noise, feedback, or any other external features that may have affected the original recording.

By understanding the critical listening phase of voice identification, you will better understand the value and importance of voice identification as a tool for the audio forensic examiner and audio forensic expert.

For more on Voice Identification, check out Ed Primeau’s latest book, “That’s Not My Voice!” available on Amazon.

Eavesdropping: Is It Worth The Risk?

Thursday, August 15th, 2013

eavesdroppingYou’re having problems at home.  Your spouse has been acting very suspicious recently. You can’t help but think that your significant other is having an affair, but lack of communication with that person makes it impossible to find out the truth.  In a desperate attempt to find out what’s really going on when you’re not around, you decide to set up audio recorders all throughout your house to use for possible audio evidence against your spouse.

This is a practice we see every so often at Primeau Forensics. We’ve received a handful of cases in which a third party requests an analysis of audio taken from digital surveillance of a private conversation. What these people don’t realize is that these actions are against Michigan’s eavesdropping/surveillance laws (laws vary from state to state). The consequences of eavesdropping on a private conversation are dire, and can lead to not only a considerable fine, but also possible jail-time.  Before we dig deeper into this subject, we must ask the question: What exactly constitutes “eavesdropping?”

The surveillance and eavesdropping statutes are determined at a state level. Some states enforce what’s known as “one party consent.” Basically, as long as one side of the private discourse agrees to surveillance of the conversation, the action is legal.  Here is a guide of which states enforce one party consent and which states enforce two party consent.

According to Michigan State Law, eavesdropping is defined as “to overhear, record, amplify, or transmit any part of a private discourse of others without the permission of all people involved in the discourse.” In other words, the person doing the eavesdropping must have consent from both parties to record the private conversation.  This is what’s known as “two party consent.”

You might be thinking, “But this is my home! I have the right to dictate privacy in my own home!” This is also not true.  Michigan State law defines a “private place” as “a place where one may reasonably expect to be safe from casual or hostile intrusion or surveillance but does not include a place to which the public or substantial group of the public has access.”  This includes an empty home. As long as the location is not somewhere the public can easily get to, it’s considered a private place.  So yes, it is even illegal to eavesdrop in your own home.

In the state of Michigan, eavesdropping is considered a felony.  The potential  consequences of these actions include imprisonment in a state penitentiary for up to 2 years, a fine of up to $2,000, or any combination of both.  Obviously, this does not include the potential fines you’d face if the violated parties request a civil case.

In case the purpose of the blogpost hasn’t become clear by now, the point is that eavesdropping is very illegal, and the consequences are very serious.  Even if you do find some juicy inside secrets, Michigan law also states that “using or divulging any information which you know or reasonably should know was obtained in violation of the wiretapping laws” is strictly prohibited.  So if you suspect something is going on at home, the risks involved with eavesdropping just aren’t worth it.  Healthy communication with your spouse is a much safer option when issues at home arise.

photo credit: Eavesdropping ( Hello Hello anyone there ) via photopin (license)

Audio Forensics: An Accurate, Arguable and Authentic Approach to Understanding Audio Evidence

Tuesday, June 4th, 2013

audio forensicsBell Labs was the first to discover that spoken word patterns and sounds could be identified and characteristics examined to identify the individual who made them. This has been a very important advancement in forensic science because the potential to assist law enforcement is well worth the effort it takes to defend the proponents and practitioners. Audio forensics is sometimes referred to by some as a ”junk science.” After over 25 years of examining, editing and clarifying audio recordings, I can attest to and scientifically prove that voice identification and audio authentication comprise an exacting science that has huge benefit to the courts, law enforcement agencies and businesses.

In the following article, I will describe what works and does not work for two of the main activities of audio forensic experts: voice identification and audio authentication. I will also review and break down the steps and processes I employ and explain why I believe audio forensics is a valuable tool in litigation.

I have been retained for dozens of court cases, as well as by corporations, to analyze and help explain various aspects of audio evidence in one form or another. Some situations required that I find the truth about the source of a threatening voice, like a bomb threat called into 911 or a sexually harassing voicemail left on a victim’s phone.

Other cases involved defendants trying to validate or disqualify a pre-recorded audio confession. Evidentiary audio recordings all have one thing in common: they needed an experienced audio forensic expert to review and either qualify (validate) or disqualify the evidence. My job as an audio forensic expert is to determine the recording’s authenticity or to identify the person’s voice.

Voice Identification Overview

I have been practicing voice identification for over 25 years. Many of my skills and principles have been learned from employment as an audio engineer. Other skills I have learned through reading and studying to develop skills and completing successful cases successfully. I believe people’s voices, just like fingerprints, can be identified through visual inspection of sound waves and spectrum analysis, as well as through critical listening skills. I have conducted voice identification for sexual harassment, workers compensation and employment harassment, as well as various threatening voicemail messages like bomb threats.

In our country today, we are guilty until proven innocent, the opposite of what our United States Constitution promises. It is my job to determine the truth about voice recordings using visual, electronic and auditory inspection of, both the evidence recording and an exemplar (voice sample taken for the purpose of comparison).

A typical case I would review might involve a telephoned bomb threat or harassing call that was recorded on audiotape or digital voicemail. After the police arrested a suspect, I would be retained by either the state (court) or defense to determine the truth about that audio recording.

The first step is to examine the original evidence and learn as much about the recording as possible. How was it created? Who created it? What machinery was involved?

Then, with the help of the court or defense lawyer, I create an exemplar of the accused voice to compare visual, electronic and auditory characteristics.

Almost every legal case I have been engaged in has allowed my report and or testimony into evidentiary status to aid with ”due process.” I believe my success rate is high due to the fact that I employ the three testing platforms outlined above.

Steady advances in computer technology have had a huge impact on audio forensic voice identification. Having experience as an acoustic engineer who has listened to literally hundreds of hours of spoken word recordings, in addition to sophisticated electronic software programs, has contributed to my success with voice identification.

One case I examined involved a bomb threat. Bomb threats make up a fairly large segment of voice identification activity. The call in question was made from a pay phone outside of a convenience store to a 911 operator. This was scientifically evident when police traced the call.

The caller identified herself by name as an employee of XYZ Company. When the police arrived at XYZ Company, they found the employee with the name the caller gave the 911 operator and arrested her. The employee denied making the call.

She was charged with making a bomb threat call, guilty until proven innocent. I was retained by the defense to prove that our client did not make the bomb threat call.

Voice Identification Procedure

When comparing spoken word samples for the purpose of identification, I base my processes on historical information I have learned from the scientific community, state police crime labs, other forensic experts and designers and developers of electronic (especially computer) equipment and testing software programs. My process requires the visual, electronic, and auditory examination of every aspect of the words spoken, not just the pathological examination. The words themselves, the way the words flow together, the pauses between the words, the way the words are formed by the mouth and larynx can be measured using three processes. The first process is a visual examination of the sound wave, comparing the evidence and an exemplar (a voice sample of the accused). The second process is an electronic measurement of the evidence, which is then compared to the exemplar. The third process is perhaps the most important: critical listening skills that compare the evidence and the exemplar of how the words are spoken and pronounced. Noise floor and electronic measurement of speech and other audible sounds in the recording must also be considered and measured. Forensic procedure requires careful examination of all audio evidence characteristics, following procedures as outlined by the scientific community.

These scientific procedures begin with the analysis of the quality of the audio recording. It is important to establish that the quality of the recording in question is acceptable and workable. Sometimes, it may be necessary for an audio forensic expert to apply some light equalization or other non-destructive audio processing to reduce or remove background noise that may interfere with the forensic examination.

Voice identification requires the forensic examiner to discover similarities, as well as differences, in all three areas of investigation.

Here are the step-by-step processes I use when conducting voice identification:

1. Visual examination of the original recording, analogue or digital. This includes examination of the physical characteristics of the tape itself (if analogue) or analogue or digital recorder. It is important to examine the cassette tape (standard, mini or micro) or other analogue or digital source to determine if there are visual signs of tampering or alteration.

2. Once the physical evidence has been examined, the next step is to load the recording in question into a forensic computer. Visual examination of the sound wave, sonogram and spectrograph reveal speech characteristics and patterns of verbal delivery as well as electronic characteristics. At this point, the recording has been digitized so forensic software can analyze and conduct various tests.

3. If possible, for authentication or voice identification, an exemplar or comparison recording should be made of the original recording to compare the original recording characteristics. This same forensic examination process that is applied to the evidence is also applied to the exemplar to determine that the characteristics are the same and the recording is from the same audio recorder.

4. When conducting voice identification, it is important to create an exemplar of the accused for audio comparison using as exact conditions and equipment as close as possible to the measurements taken from the evidence as outlined above. The speech must be the same as the speech on the evidence in order for the testing to be accurate. As an audio forensic expert, I often have to coach the accused into the same energetic voice tone and inflection as the evidence recording. However, it is still possible to compare speech if the exemplar is not as close to the evidence as I would like.

5. Critical listening skills are used to examine the speech pattern, pronunciation, voice tone and inflection, accent, dialect and specific speech characteristics (like a lisp or significant ”s” delivery). There is a rhythm in how an individual speaks, and even if s/he is trying to disguise his/her speech (in an attempt to fool the forensic examiner), the rhythm and speech patterns as described above still show through. The expert must pay careful attention to the rhythm of spoken word formations. I listen to single words as well as phrases and sentences. I like to compare original evidence sections of spoken word recordings as well as individual words. This is best accomplished by editing exemplars and original recordings back to back. It is extremely helpful to then make these sub files of words and sentences within the section back to back with exemplars. I repeat the assembly over and over to accommodate critical listening skills with the auditory identification process. That way, your ear can experience the sounds, vowel formations and consonants without interruption.

There are many character traits that can be experienced in a spoken word recording. It is important for the audio forensic expert to become familiar with the evidence speech patterns and visual and electronic characteristics. These characteristics are evident in a person’s voice even if he or she attempts to disguise it and they are compared to the exemplar.

Audio Authentication

Using many of the same tools as described above, audio authentication can help determine the validity of audio evidence that is being considered as evidence in litigation.

When authenticating an audio recording, it is important that the audio forensic expert pay careful attention to tone consistency of the audio recorded signal (speech) as well as the recording’s noise floor.

The consistent audio-recorded signal is important because audio recordings that are not authentic are most always edited or fabricated assemblies of two or more audio recordings for the purpose to deceive the person(s) listening to the recording. Using the tools described above, the audio forensic expert can measure the tone consistency to determine authenticity.

Those same tools can also measure the noise floor looking for inconsistencies in the room tone or background noise of the recording. These breaks or changes in either audio recorded signal or background noise are signs that the audio recording being considered may be counterfeit or fake.

Critical Listening Skills

I have been working with professional speakers and analyzing other spoken word recordings since 1980 and have developed my critical listening skills to a degree that far exceeds the average person’s sound perception. When I first hear audio evidence and add exemplar recordings so I can listen to both back to back, then I apply my critical listening skills to determine the speech similarities as well differences between the two.

In my early days as an audio engineer, I learned to edit reel to reel tape with razor blades to make a recording sound as if it were recorded start to finish without a single mistake. Some of my edits were pretty tricky. I got so good I could split words in two and even three edits to fix a problem or shorten a script. After a while, I became very familiar with speech characteristics and patterns as well as vocal tone and pronunciation.

The best way to become skilled in voice identification is to listen to hundreds of hours of forensic evidence to become familiar with the various speech pathological characteristics and develop critical listening skills.

There can sometimes be differences in speech patterns that can help identify clues. Listen for several similarities as well as differences, such as nasal resonance differences and voice tone with regard to inflection.

Voice Identification Conclusions

When conducting the examination, the audio forensic expert must look for similarities as well as differences in all three testing platforms to help arrive at a conclusion.

After the investigation and testing procedures are complete, the forensic experts report must arrive at one of the following conclusions: positive identification, probable identification, positive elimination, possible elimination or inconclusive.

The key to successful voice identification is to develop a methodology and standard procedure that you strictly follow every time you conduct an identification and comparison.

Audio Authentication Conclusion

Every tone change in either the audio recorded signal or background noise must be documented and analyzed as a whole before considering the recording genuine or authentic. All forensic concerns must be documented and listed in the forensic report to prove the audio forensics findings.

The Audio Forensic Report

It is my belief that the audio forensic report should include:

1. The introduction: What the expert was asked to do and how the expert arrived at their conclusion, including all scientific fact.

2. The testing processes you employed to ex- amine the audio evidence.

3. The expert’s conclusion of the tests, includ- ing the expert’s opinion as to the relevant facts and concerns.

4. The expert’s curriculum vita (resume) to establish credibility as an audio forensic expert, and to accommodate the Federal Court’s protocol for submitting an expert report.

5. A published article authored by the expert concerning the kind of testing relevant to the current case.

For more information contact Ed Primeau at 800-647- 4281 or by email Ed@PrimeauProductions.com.

photo credit: 18v via photopin (license)

Ed Primeau works with FBI on the S. Jerome Bronson case

Thursday, May 30th, 2013

FBIIn 1986, Franklin-based Judge S. Jerome Bronson was arrested for accepting a $20,000 bribe.  Once arrested, he was released by Ingham County Circuit Judge Thomas Brown, and subsequently ended his own life.

Judge James N. Canham acted as a middleman, and exposed Bronson by wearing a hidden microphone when presenting Bronson with the $20,000.

This is one of the first cases I ever worked on as an audio forensic expert. Back then, there were no digital means of voice analysis.  Software programs to enhance audio quality, create digital duplicates, and make edits did not exist. The original recording was presented to me on Reel-to-Reel and created on a NAGRA tape recorder.  This was entirely analog sound, so to analyze the recording, I was limited to a physical rack of outboard gear such as equalizers, compressors and limiters to get the job done. Once I had made enhancements, a direct copy of the enhanced recording had to be presented on reel-to-reel.  Nothing was automatic; everything was manual.

Below is a news article from The Argus Press about Bronson’s suicide. It’s simply amazing how far technology has come in my 29+ years of audio analysis, and how far it could possibly go!

photo credit: J. Edgar Hoover FBI Building via photopin (license)

Audio Forensic Expert Report Writing

Monday, May 6th, 2013

forensic report writingAll forensic experts write reports. Some reports are better than others. What goes into a ‘better than other’ forensic report? Depending on the forensic investigation, opening the forensic report with the credibility building language is an important starting point. Here is a sample of how I open my audio forensic reports:

I am an audio forensic expert and have been practicing for 29+ years. I have testified in several courts throughout the United States and worked on various international cases. My forensic practices include audio authentication, restoration and voice identification.

The next step in the forensic report is to include the evidence you were provided by your client to forensically examine, as well as what you were asked to do. This paragraph must be documented and described in detail. Here is a sample of how I draft this section:

On or about March, 25, 2011 I received a CD from your office that contains a 911 call recording. You asked that I investigate the recording to determine if it contains one or two voices at the scene of the crime.

I listened to the CD and heard the initial voice that spoke and the second questionable voice in the background, noting that it sounded different from the first voice. I suggested making arrangements to create an exact exemplar of the suspect for comparison purposes in this forensic investigation.

On Tuesday, April 23, you and I arranged to create an exemplar of the suspect’s voice to comparewith the initial 911 call first voice. The exemplar was created using as much of the same electronics as possible that were used in the original 911 call recording. Also featured in the exemplar were the exact cell phone and the same person that placed the original 911 call.

In addition, we also recorded exemplars of other persons who could have made this 911 call for comparisonpurposes in a voice identification line up.

 

This above outline is an example. Much of the language might not make sense but the text still exemplifies the message I am communicating about audio forensic reports.

The next part includes your investigation; what you did as an audio forensic expert and the opinions you arrived at. This investigative process must list all activity, testing and the software programs, hardware and other tools, scientifically describing in detail all tests so that another forensic expert with similar qualifications can recreate your testing and arrive at conclusions.

In a case where the opposite side in the litigation has retained a forensic expert, that forensic expert will want to review your investigation and findings to determine how to strategize the court proceeding based on this information as well as your opinion. I have worked on cases where the forensics experts were disagreeing with each other before the trial, and others where forensic experts were disqualified before trial. This is why forensic report writing is crucial and one of the most critical parts of any forensic investigation.

The fourth component in the forensic report is the expert’s conclusions; often times this conclusion is ‘based on a reasonable degree of scientific certainty’. The audio forensic expert reports the truth about the evidence in question or another characteristic in question about the audio evidence. The conclusion is a statement of scientific fact and opinions expressed about the conclusion of scientific fact must be presented in simple English for all triers of fact and other expert witnesses to easily understand.

When the forensic report is submitted, it should also include any work product, sub files and the most recent CV (curriculum Vita). If the case is older, chances are the expert has updated their CV since beginning the forensic investigation.

If you have an audio forensic concern and would like more information about the investigating process with regard to report writing, call or write for a pro bono consultation.

George Zimmerman or Trayvon Martin; Who Cried for Help?

Wednesday, May 1st, 2013

trayvon martinAfter a year it’s pretty apparent there were two people present when Trayvon Martin was killed, Trayvon Martin and George Zimmerman. The question still remains; who screamed for help the night of February 26, 2012 and why is this important?

If it’s Zimmerman who is screaming, it exemplifies that he was the one under attack by Trayvon. If the screaming is Trayvon Martin, then this would add to previously revealed adverse behavior by Zimmerman acting aggressively toward Trayvon. Remember, Zimmerman ignored the police when they told him not to follow Trayvon.

As the State of Florida v. Zimmerman begins to heat up, forensic experts for the prosecution and defense are ready to begin the voice identification testing process to determine who cried for help the night of February 26, 2012.

The human voice is unique to each person and can be examined through the process of voice identification to discover identity.  Voice identification testing has become more acceptable in the courts and will be a valuable part of this trial. Scientific processes for voice identification testing include critical listening and spectrographic analysis. Both visual and aural inspection and interpretation of the evidence and exemplar (speech sample of the suspect’s voice) are examined. The problem with this case is the lack of significant speech from the unknown person who cried for help. Voice identification typically requires a minimum of 20 words spoken for comparison purposes. In this case we are testing screams which is much more difficult.

Yesterday, April 30, 2012 the court has asked experts for the prosecution and defense to produce any enhanced recordings they have of the call to police by Zimmerman. I believe the court is attempting to understand and identify all audio evidence that is available to aid forensic investigators.

So far we have been told that there are no audio or video recordings of Trayvon Martin. Therefore audio forensic experts can only use voice samples, previous recordings and exemplars that are available to conduct a voice identification investigation and eliminate or identify George Zimmerman as the source of the cries for help based on a degree or percentage of professional certainty.

The first step in any voice identification test is to aurally listen to evidence and exemplar recordings edited back to back using critical listening skills developed over the course of the expert’s forensic career. In the video below I have edited back to back audio samples taken from the police call by Zimmerman the night of February 26, 2012 when Trayvon was killed and an exemplar or reenactment recording of George Zimmerman created by the authorities.

In a perfect world, audio forensic experts listen for isolated speech sounds like vowels and consonants for their uniqueness’s, similarities and differences as well as phrases and sentences. Pronunciation of words are noted, the way words flow together and speech characteristics like accent and dialect, age and gender or nationality and noted.

In this case, the audio forensic expert only has screaming to compare and identify. Yes this is possible and very important to this case. Based on my experience, the voice identification test results will include a percentage of certainty because of the lack of audio recording and speech available for voice identification testing.

photo credit: IMG_2110 via photopin (license)

Audio Enhancement from CCTV

Friday, April 26th, 2013

CCTV CameraRecently I have been asked on several of my forensic investigations to enhance the audio recorded on CCTV video surveillance. Audio can be very useful evidence in addition to CCTV surveillance video in the court room. Audio helps fill in the missing components that help the court review the series of events as they occurred.

Some of the video evidence I review must be viewed in a proprietary video player created by the manufacturer of the CCTV system. Other video evidence like smart phone video and some CCTV recordings do not require a proprietary player. Either way, as an audio video forensic expert, I have the skill and experience to know the best way to extract that audio recording and enhance it so that the triers of fact know more about the circumstances surrounding the criminal activity or litigation.

I have found that what is not captured on video by the CCTV system cameras may be captured on the audio portion of the same recording.

Once the audio track is extracted using a video software program, the digital audio file is imported into one of my audio software programs. One of the first steps is to increase the volume of the recording. The next step is to remove any unwanted background noise that distracts the listener’s sound perception. This process is often repeated until a desired outcome is achieved.
I also use other tools to help further enhance the audio recording like equalization, compression and notch filtering.
If you have any questions about audio enhancement or sound restoration from video surveillance call us at (800) 647-4281.

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