Audio Enhancement – A Forensic Approach

audio enhancementThere are two ways to look at audio enhancement, from a recreation standpoint and a business/legal standpoint. Most people searching for audio enhancement are looking for a solution to better hear a poorly recorded audio conversation. The audio recording may or may not be a very important piece of audio evidence.

The term “audio enhancement” can be used for a couple of different situations. First, with regard to ‘enhancing’ the quality of the listening experience – let’s call this ‘passive’ audio enhancement, since the goal is simply to enjoy a recording in the best possible environment. I am an audiophile; I love great sound when I listen to music. In that regard, audio enhancement is the activity of choosing the right equipment, careful placement of the speakers, careful placement of the furniture and taking your time gently balancing the equalization and stereo imaging.

Audio enhancement also helps a sound projection situation in sounding the best it possibly can. These situations can include a church service, professional speaker seminar, live concert, symphony or even a drive in theater. Yes, I believe drive in theaters will make a comeback.

In this situation, audio enhancement involves choosing the right speakers, then identifying the perfect placement for them with regard to sound source and audio ratio to audience. Live sound audio enhancement also involves activity as outlined in the previous example, like balancing the equalization and stereo imagery.

Audio enhancement for forensic applications, also known as forensic audio enhancement, also has similar activity as outlined in the previous samples – we’ll call this ‘active’ audio enhancement, since we are actively manipulating the quality of the recording itself in order to clarify what is being said. This activity requires a much more sanitary environment. An audio forensic lab is acoustically tuned and well stocked with the finest hardware and mind boggling software. This software is used in a specific order that is defined by each individual enhancement situation or court case.  With regard to audio enhancement for forensic applications, it is the skill of the audio forensic expert that makes or breaks audio enhancement success.

After 30 years of enhancing audio forensically, we are often asked by clients why our success rate is so high. I tell them that we began their enhancement process by analyzing the various reasons why their audio recording was so poor. Was it because background noise was louder than the desired conversation? In this case our goal is to clarify a recorded conversation. The audio forensic expert then determines whether to remove background noise first or boost the overall volume. With some cases the audio expert may apply other filters first like equalization, compression or re-sampling in order to better hear the words spoken.

There are free software programs available that do a pretty good job enhancing recorded conversations. Primeau Forensics recommends an audio software program called ‘Audacity.’  Audacity has equalization, format conversion and some similar processes and filters that other professional software programs have that we use at Primeau Forensics, like Adobe Audition. This is one approach if funds are low.

The problem then becomes maintaining a chain of custody. If your recordings are to be used in court, establishing a chain of custody is extremely important. It does not look good to the other side when you use a software program yourself. This is why most people in need of audio enhancement seek assistance with a company like Primeau Forensics.  Not only do we enhance audio and establish a chain of custody, we also create a forensic transcript when necessary that is signed and certified by an audio forensic expert. This forensic transcript is then used with the enhanced audio evidence to create a packaged piece of evidence that is more powerful than the enhanced audio alone.

We have experienced situations where the playback systems in court, as well as the reverberant acoustics, make it difficult to hear the enhanced audio recording. When the enhanced audio recorded evidence is accompanied with a certified forensic transcript, the judge and jury can read along with the transcript. It allows the court to better hear the enhanced recording.

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