Posts Tagged ‘Audio Forensic Expert’
Audio Forensics: An Accurate, Arguable and Authentic Approach to Understanding Audio Evidence
Bell 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.
Audio Forensic Expert Report Writing
All 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 includeaudio 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?
After 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.
Audio Enhancement from Video Surveillance
Recently I have been asked on several of my forensic investigations to enhance the audio recorded on the video surveillance. Audio can be very useful evidence in addition to 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 from video surveillance call us at (800) 647-4281.
Crisis Management and Voice Identification
Historically, voice identification has had its ups and downs in the United States Courts. Forensic experts that practice voice identification follow voice identification processes that have been established in the scientific community. However, there are times the voice identification process is necessary with less than perfect circumstances.
In my opinion, especially under less than perfect circumstances, the voice identification process is not always black and white. Litigators need help building a case to either prosecute or defend and some of the main evidence is voice recordings. A majority of the time these voice recordings are threatening and disturbing to the recipients who are targets to the threats left in these messages. Some messages are longer than others – it is the short messages that pose the biggest challenge for voice identification experts.
According to the scientific community, in order to conduct voice identification, the following process is followed by the audio forensic expert:
- Make sure the unknown recording has sufficient amount of words
- Make sure recording is clear and free from noise
- Sufficient frequency range of recording (telephone calls are leader in lack of frequency)
- Exact exemplar creation using available exact electronics
- Multiple exemplar recording samples of suspect’s voice
- Test aural (listening-single and multiple word formation) and spectrographic (visual-electronic measurement)
- List all similarities and differences for both aural and visual testing
- Create comparison back to back sample file using evidence and exemplar samples
There are five standard conclusions:
- Positive identification
- Probable identification
- Probable elimination
- Positive elimination
- Inconclusive
In order to arrive at a positive conclusion, the audio forensic expert must find a minimum of 20 speech sounds and/or electronic/spectrographic identifying or disqualifying characteristics. However in the case of a crisis, investigators ask voice identification experts to determine as exact as possible what percentage of certainty can be established with regard to what I consider nontraditional voice identification. In this case I follow as much of the established protocol as possible and provide a percentage of certainty in my findings.
Threatening calls in the workplace require the identity of the caller be revealed or at least narrow down the list of suspects so management can take appropriate actions to protect other employees. These threatening calls are most always short, which presents challenges to the forensic expert due to the number of words available to be compared to known speech samples. In this case the voice identification examiner needs as much exemplar (known speech) recording as possible to use for comparison purposes.
I consider these threatening phone calls and messages to fall under emergency ‘crisis’ situations and adjust the voice identification procedure to accommodate the client and attempt to identify two or three suspects.
Another tool that helps the audio forensic expert in these crisis situations is the voice identification line up. In this style of voice identification testing, it is necessary for the voice identification expert to create a comparison file with back to back samples taken from all suspect exemplar recordings. This comparison digital audio file can be closely examined very quickly noting all similarities and differences to determine a suspect.
Many companies have a database of absenteeism calls from employees. These voice mail recordings are great alternates to exact exemplars because they were recorded through the phone similar to many of the threatening calls. For this reason, I recommend that companies maintain a voice mail recording database for crisis management cases like these. Then when the voice identification expert is called on to provide their opinion about the suspects for investigators to consider, the voice identification expert can help strategize additional steps and strategies to take that will help solve the mystery.
I have found that once a suspect has been identified preliminarily and asked to cooperate in creating an exact exemplar, they either confess or investigators discover additional clues to help with the crisis investigation.
In one particular voice identification case, my preliminary testing helped reveal two suspects. We discovered that the threatening call was made from a company phone. There was a CCTV camera near the company phone which provided video of one of the suspects near the phone the day and time the threatening call was made. The identification could not have been made without the preliminary nontraditional voice identification test that helped identify two suspects. That helped me know who to look for in the CCTV video. The CCTV digital video recording was poor but I was able to identify clothing logos on the person in the video with the suspect who often wore similar clothing. Investigators were able to leverage a confession once the suspect was confronted with this preliminary evidence.
So, although formal voice identification is not always possible, an audio forensic expert can aid in the investigation of threatening voice mail messages and help keep the attacked workplace safe for other employees. When the case reaches a point when a formal charge is made, the voice identification testing can then be directed to traditional testing protocols.
Release or Destroy Audio Evidence After Litigation
An audio forensic expert listens to audio recordings of litigation points during a forensic investigation. Oftentimes, these audio recordings are very sensitive in nature. They are crucial to the litigation and must be destroyed or returned to their provider once the litigation is complete. Generally, in civil litigations, settlements are reached based on a series of conditions. One of those conditions is often that all of the evidence be destroyed that was used to process that litigation. It is very important that the audio forensic expert stay in good communication with their lawyer contact to make sure that they clearly understand what to do with the audio evidence once the litigation is complete.
If that audio evidence were to become available to the wrong people after the litigation settlement it could violate and have other ramifications to the terms and conditions of the settlement. That’s why it is very important for the forensic examiner to know what is expected of them from the attorney and other litigators regarding that forensic evidence.
In the past I’ve received letters from attorneys asking me to dispose of the audio evidence I used to investigate their case. In my professional opinion, there are only two options for an audio forensic expert for dealing with the evidence they examined upon reaching a settlement in the litigation.
One, return the evidence back to the attorney or your contact person in the case. Signature required, delivery confirmation is essential so that the forensic expert has proof that it was returned to the appropriate party. Second, destroying the evidence by physically breaking or destroying the playing surface on a compact disc, which is the most common media for delivering the audio recordings to be examined by the forensic expert. Or delete files stored in computer hard drives or other external storage devices, such as a thumb drive.
So, we either return the evidence to the contact person, signature required so that we have confirmation and proof of delivery; or we dispose of the evidence by destroying the compact disc or delete from external storage device. It is best, if possible, to get their instructions in writing (particularly if the instructions are to destroy the evidence), just to protect yourself and make sure all your bases are covered.
I recently had a case that settled and I was contacted by someone who identified himself as a friend of one of the litigators, and claimed to have permission to listen to part of the audio recording that I investigated for this litigation. I denied the (alleged) friend access to the recording and contacted the party who retained me for the investigation and let them know I was being contacted. The huge problem here is that, had I given the audio evidence to the person that contacted me not only could I have jeopardized my reputation in the forensic community if this person had released that evidence, it would also have had a huge ramification on the settlement for my client because, that audio evidence being compromised, would also violate the conditions of his litigation settlement (not to mention opening myself up to a possible lawsuit for releasing the audio evidence to an unauthorized party).
Bottom line, when the forensic expert completes a forensic examination, it is the forensic examiner’s responsibility to determine what to do with the evidence that they have investigated so that it does not fall into the wrong hands and violate the terms of the litigation settlement.
Forensics Education and Networking
Courtesy of FreeDigitalPhotos.net
Last week I attended the American College of Forensic Examiners international conference, the Executive Summit, out in Las Vegas at the Rio. The conference was well attended and covered many different forensic curricula, but the one session that really motivated me to attend this conference was Tom Owen’s presentation about his perspective on the Trayvon Martin audio identification. Back in April 2012, Tom and I were asked by the Orlando Sentinal to provide our opinions on whether or not the cry for help in the background of a 911 call was the voice of George Zimmerman, who had told police that it was him screaming for help. Both Tom and I agreed that the voice was not George Zimmerman’s. I went further and told the media that I believed the voice was that of Trayvon Martin because of the known facts of the circumstances. In my opinion, and based on my experience, that voice sounded like a young man’s voice. It had the pitch and the tone of a young man, as opposed to an older man, and the voice just did not fit the demeanor of George Zimmerman, based on all of the dialogue that I had available to examine. Neither one of us could come to a positive conclusion because we were not given any voice samples of Trayvon Martin. And, again … this was all about our opinion.
So I attended this conference and watched Tom’s presentation, in which he did a fabulous job, and was very captivated by the audience of attendees. Afterwards I spoke to Tom for a few minutes and he invited me to sit in on the American Board of Recorded Evidence board meeting that they were about to have on property at this conference. Since my flight on the red-eye wasn’t scheduled until midnight, I had plenty of time and gratefully accepted Tom’s invitation. During the board meeting I agreed to be on three sub-committees to help advance the credibility of our forensic designations.
One committee was for voice identification, one was for audio forensics and the third for video forensics. And we have quite an agenda established over the next year in order to lend more credibility to qualified audio and video forensic examiners. It was an honor to be invited to sit on this board with the best of the best in the audio and video forensic community. In fact, at the end of the board meeting we shared ideas and software techniques openly and candidly, which was very informative for everyone involved. Afterwards we went to dinner and continued our conversations about the industry, discussing ethics and qualifications and certification programs and other activity that will help strengthen the value of an audio or video expert in litigation.
It is truly an honor to be able to serve on a board with peers that are the best of the best forensic experts in the private sector. I look forward to further learning and development as a forensic expert and advancing my career and the careers of others through feedback and participation on the American Board of Recorded Evidence.
Audio Enhancer Tips for Concealed Recordings
As an audio forensic expert, I receive audio recordings that were created in noisy public environments. One of the activities that I am often asked to do is to enhance these audio recordings so the conversation can be clearer and can be used in litigation. One of the tips that I would like to offer in this post is this: an ounce of prevention is often the best remedy. In other words, instead of putting the audio recorder in your pants pocket, purse, briefcase or other type of bag, consider wearing a garment that has a lapel pocket where the digital audio recorder can be easily be placed. Placing the digital audio recorder in the lapel pocket of a shirt or sport coat allows the microphone to be closer to the sound source or conversation than if it were placed in a bag or briefcase under the table or on the floor.
A second tip is to consider the recording location. Oftentimes when litigators create concealed recordings, they meet the opposing party in a public location. Public locations tend to be noisy, so the recorder picks up the noisy background disturbances in addition to the conversation that’s important to the litigation. When you choose the public location to record your conversation, pick the quietest spot at the location. Arrive early so you—the person creating the recording,—can choose the quietest spot at the location. Listen carefully when you walk into the location and find the quietest spot or table to sit at when creating your recording.
The third tip is to make sure that your recorder is functioning properly. Many conversations are lost because of a low battery, a microphone pointing in the wrong direction, or not enough space on the memory of the recorder. So before you make your concealed audio recording, make sure you have fresh batteries in your recorder and make sure the folder you are recording your conversation into has plenty of space for the duration of your conversation. (You can check this by looking at the manual for your recorder and determining how you can assign your folders for the most optimum use of your storage space.) You also want to make sure that you have enough storage space left on your digital audio recorder. Delete any recordings that are not needed—or, if the conversation is valuable, purchase a new digital audio recorder. Olympus is one of the most reliable manufacturers of digital pocket recorders.
These audio enhancer tips for concealed recordings will help you to successfully create a recording of your conversation for use in litigation. And remember: do NOT delete the original recording from your recorder in case there is ever a question of the integrity of your concealed recording.
For more information call 1-800-647-4281.
Audio from Video Evidence Offers Additional Clues
Audio and video forensics go hand in hand in a lot of today’s litigations. As an audio and video forensic expert, I work for both the prosecution as well as the defense. Lately I’ve been working more for the prosecution and I am seeing audio and video evidence being used more often to prosecute cases than ever before. Traditionally defendants would contact me because they believed the police had altered audio and video evidence that was being used in the prosecution’s case. As an expert of almost 29 years, I think about that when I’m contacted by these defendants and wonder why a police officer would risk his reputation, his retirement and his entire career by altering evidence in order to convict. But it’s still my job to authenticate and to investigate when I am asked.
Recently I worked on a case for a police department where there were questions about who said what on a dashcam video. This is where the audio and video forensics intersect in litigation. The dashcam was static and nothing could be seen regarding the series of events as they occurred. However, the microphone in the car and an officer’s microphone were on, allowing the video to record the audio of the situation. What was in question was who said what in the recording. I was able to get samples – or exemplars – of the voices of the people that were at the scene of the crime and compare them to the voices that were recorded on the dashcam video. I had my assistant create a transcription and we started with “voice one, voice two, voice three” because the voices were significantly different (which isn’t always the case). They were different enough that the listener could determine three separate distinct voices. These differences were also an advantage because the voices were all male, which sometimes makes it difficult to differentiate between the parties being recorded. By creating a transcript and determining through voice identification investigation, I was able to recreate what the camera did not see through an audio forensic process.
So when prosecuting a case, it’s important to consider both audio and video aspects of the investigation even if the video may seem hopeless. When you work with an audio and video expert, that expert can give you some advice and ideas of clues that could be picked up in the evidence to help your case. Even if the clues start out small, they may turn into evidence that can be used to help prosecute. The clues will at least bring some more truth into the courtroom, which is the job of the audio and video forensic expert.
The Why and How of Audio Evidence Integrity
When audio recordings are used in any litigation, the integrity of the evidence is not only important, but oftentimes questioned. It’s crucial to consider evidence integrity before you present your evidence in court.
As an audio forensic expert, I am often asked to authenticate audio evidence for litigations. This authentication process provides integrity for the audio evidence and strengthens its weight in the litigation.
For example, it is easy for just about anyone who has some basic computer skills to alter audio evidence by removing portions of the recording that they don’t want the litigators to hear. Although this is not a common practice, it has a huge impact on the credibility of the audio evidence being presented. The reason is as simple as this: the altered audio recording is not an actual representation of the facts as they occurred. Portions of the actual evidence have been removed.
This is similar to missing evidence from a crime scene. What if a police officer arrived at a crime scene and began moving or removing items from the scene? How would the crime scene investigation team know the actual facts of the crime as it occurred without all the evidentiary items at the scene?
Once the integrity of the evidence has been compromised, the audio component of the litigation is reduced to “he said, she said” – my word against theirs.
Police officers have been trained to maintain evidence integrity at the scene of the crime. However, people who submit media evidence like audio and video recordings may not completely understand how important it is to maintain evidence integrity.
Tips to maintain integrity:
1: Keep originals in a safe place.
2: Photograph or video record any specific activity information.
3: Retain a forensic expert to help you document the authenticity of your evidence.
