Audio Enhancement Services, Voice Enhancement

What is Audio Enhancement?

Audio enhancement is the scientific process of clarifying audio recordings using non destructive techniques to preserve speech intelligibility so that the trier of fact can make determinations about the events within the recording. One of the goals of forensic audio enhancement is to better hear dialogue by removing unwanted noise. This scientific process is also known as speech enhancement and voice enhancement.

Audio enhancement techniques are applied to remove unwanted noises like static, furnace and air conditioning fans, hums and other distracting sounds. These distracting noises are also known as “unwanted sounds”.

Then, once the unwanted sounds have been removed, audio enhancement processes can be applied. These enhancement processes will increase the “wanted sound” like speech. The enhancement processes will increase voice quality and dialogue intelligibility through signal processing. Our forensic audio experts apply forensic audio enhancement services to increase the intelligibility of your audio recordings used as evidence in court. 

In addition, the same is true for for the audio quality of a video clip. We also perform forensic audio enhancement on video recordings like police dash cameras, body cameras, Ring CCTV devices. That is why we have additional information for your review here” how to enhance audio in a video file. 

Audio Enhancement Process

Types of Recordings for Audio Enhancement

So you better understand, we perform audio enhancement on a variety of audio recordings. These including but not limited to:

  • Recordings made on smart phones
  • Deposition video
  • Digital handheld recorder
  • Digital pocket recorder
  • Cassette tape
  • Micro & mini cassette tape
  • Law enforcement dash cam
  • 911 dispatch
  • Courtroom recording
  • Confidential informant
  • Wire tap
  • Voice mails

Forensic Audio Enhancement Methodology

How to enhance an audio recording?

Critical Listening

critical listening for audio enhancementCritical listening is a skill that is developed over time through training of the ears. It is key for identifying sections of the recording that require audio enhancement. This is based on the audio files original characteristics which include levels, frequency ranges, or signal to noise ratios. Critical listening can be performed with both speakers and headphones.


equalization for forensic audio enhancementEqualization is a filtering process that can reduce unwanted frequencies or increase wanted frequencies. Distracting noises can interfere with other forensic processes and must be filtered first to ensure the highest success of the enhancement. Equalizers are commonly used to filter out hums, buzzes, a/c compressor noise or other unwanted tones that are banded noise.

Noise Reduction

forensic audio enhancement

Noise reduction improves the signal to noise ratio by reducing distracting sounds from a recording. These distracting sounds hinder the speech recognition ability of the listener. Noise removal is the most effective processing technique for voice enhancement. The noise reduction process uses a noise profile to systematically reduce unwanted frequencies without affecting the dialogue or human voice signals.

Compression/Gain Adjustment

Compression will usually be applied next to raise and balance the  volume levels of a given section. Gates and further compression can also help remove unwanted sound or boost desired sound. If there is excessive background noise, a gate can be helpful before most of the other processors, especially compression.

Forensic Transcription

The forensic transcript may become essential for verification of dialogue spoken or events that occur in the recording.  The forensic transcript combined with the speech enhancement or voice enhancement makes an exhibit more relevant to an investigation.

Enhanced Audio Courtroom Use

forensic audio enhancement in the courtroom

Often times when a lay person processes an audio recording, these changes can effect in a negative effect. The authenticity of the events change, and inaccurate representation of the events makes the recording inadmissible in court. This is often times based on an inaccurate perceptual quality change.

A qualified forensic expert must follow the best practices established by the scientific community. This includes performing the audio enhancement services accurately, documenting the procedures used and presenting the findings to the Trier of Fact. An successful speech enhancement is used to identify dialogue as it originally occurred.

Click HERE to learn about what some of our clients have said.

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