Blindspots of Forensic Analysis

One of the most common jobs for an audio forensic expert is enhancing a digital audio recording for intelligibility and clarification.  Audio evidence is often recorded in less than optimal situations with poor quality equipment. This evidence can be vital to a case and when the content of the recording cannot be heard, the evidence can become useless.  This is why the audio enhancement process is one of the most important jobs as an audio forensic expert.

There is no one way to enhance an audio recording because every recording is different and will have its own issues that make the enhancement process necessary. At the same time, it is important for the Forensic Expert to be aware of the processes available so they are prepared to handle any enhancement case that comes their way.

Critical Listening

To begin the enhancement process, the Forensic Expert should use critical listening.  Before adding any processing to the audio, they should listen through the recording multiple times and make notes on the issues they hear with the recording.  Noting different sections of the audio and marking these points can be extremely helpful when fixing different problems in the recording.

Diagnostic Tools

Some audio software includes processors that help fix clipping or clicking issues in the recording.  Using this process first will help clean up the audio as much as possible before delving into more advanced techniques.  Noise reduction is also a very helpful process for removing any background noise such that it is consistent throughout the recording.

Dynamics Processing

Many recordings I receive have an overall low level, to begin with, and simply need an increase in gain. Compressors, as well as gain plugins, can help raise the overall level of the recording. Compression will also help balance all of the signals in the recording.

Equalization

Equalization is another extremely helpful tool for audio enhancement.  This will allow the forensic expert to remove unwanted frequencies and frequency ranges by varying amounts, as well as boost desired frequencies. When using an equalizer, the Forensic Expert should experiment using their knowledge of frequencies and what they see in the recording.

Now listen in with audio and video forensic expert, Ed Primeau, as he discusses the structured approach to forensic audio enhancements.

Video Surveillance expert David Spreadborough is a CCTV investigator and a police officer for the Cheshire Police Department in Cheshire, England.  He has been a part of the police force for 23 years and began his video forensic career in 2003.  David is a member of the Law Enforcement & Emergency Services Video Association International (LEVA), the National Policing Improvement Agency (NPIA), the CCTV National Standards Forum and he sat on the Association of Chief Police Officers (ACPO) Working Group for CCTV.  David has taken multiple training courses covering Forensic Video Analysis, CCTV installation and retrieval, and Multimedia Evidence Processing. He focuses on CCTV video evidence and has spent the last few years working with CCTV manufacturers to improve the quality of systems as well as the installation and accessibility for law enforcement.

Up until November of 2014, David was the Senior Officer within the Visual Forensic Unit in the Cheshire Police Department and oversaw all major crime video investigations in the department.  It was then decided that Police Officers could no longer hold Forensic positions within the department.  David is currently looking forward to finding new ways to use his expertise as a Forensic Video Investigator and welcomes anyone who is interested in learning more about the field to contact him.

David is dedicated to the development of Forensic Video Analysis and working with new technology to improve the field.  If you would like to contact David, you can find him on LinkedIn.

Suggested additional reading on video evidence recovery HERE!

Now listen in as Audio and Video Forensic Expert Ed Primeau and Officer David Spreadborough discuss the importance of CCTV systems for law enforcement, the advancements made in video surveillance over the last decade and the challenges being faced by Video Forensic Experts today.

Video Surveillance with David Spreadborough

Video surveillance expert, David Spreadborough, is a CCTV investigator and a police officer for the Cheshire Police Department in Cheshire, England. He has been a part of the police force for 23 years and began his video forensic career in 2003. David is a member of the Law Enforcement & Emergency Services Video Association International (LEVA), the National Policing Improvement Agency (NPIA), the CCTV National Standards Forum and he sat on the Association of Chief Police Officers (ACPO) Working Group for CCTV. David has taken multiple training courses covering forensic video analysis, CCTV installation and retrieval, and multimedia evidence processing. He focuses on CCTV video evidence and has spent the last few years working with CCTV manufacturers to improve the quality of systems as well as the installation and accessibility for law enforcement.

Up until November of 2014, David was the Senior Officer within the Visual Forensic Unit in the Cheshire Police Department and oversaw all major crime video investigations in the department. It was then decided that police officers could no longer hold forensic positions within the department. David is currently looking forward to finding new ways to use his expertise as a forensic video investigator and welcomes anyone who is interested in learning more about the field to contact him. David is dedicated to the development of forensic video analysis and working with new technology to improve the field. If you would like to contact David, you can find him on LinkedIn.

Listen and Subscribe to the Podcast

Now listen in as audio and video forensic expert, Ed Primeau, and Officer David Spreadborough discuss the importance of CCTV systems for law enforcement, the advancements made in video surveillance over the last decade, and the challenges being faced by video forensic experts today. Subscribe to receive the latest Blindspot episodes downloaded to your computer or portable device.

Maria do Carmo Gargaglione is the Director of the Division of Digital and Technological Forensic Evidence at the Public Ministry of Rio De Janeiro.  She has been a speech-language pathologist for over thirty years.  She is an expert in voice identification, facial identification, and handwriting analysis.  She began working in forensics in 2000 and began working for the Public Ministry in 2005. Since then, she has continued her education in the field of digital media forensics at any given opportunity, including the courses at the National Center for Media Forensics at the University of Colorado.  She was the first in Brazil to begin a division of digital media evidence with voice identification.

If you would like to contact Maria do Carmo, she can be reached by email at [email protected].

Now listen in as Maria do Carmo and Ed Primeau discusses different techniques used for voice identification, the importance of digital forensic work in Brazil, and advice for people interested in starting a career as an Audio Forensic Expert.

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