As with video and CCTV, audio recordings are becoming more common as forms of evidence in modern crime investigation.

But high-quality audio recordings are often not available, and this is where FVS can help. Our expert analysts use a variety of techniques to enhance recordings that can bring out details and provide a clearer picture of what has happened, or make an audio recording more audible.

Enhancement of the audio recording.

By re-processing audio recordings FVS can bring out additional details. For example, an audio recording with a distant background track (such as two people talking at different distances from the microphone) can have the background track ‘brought forward’ into greater clarity. Ambient noise can also be cancelled out and reduced.

 Audio Authentication

This entails analysing digital audio files to determine if any of the audio recording has been edited out, the background noise is consistent, and if audible and inaudible tones/sine wave traces remain consistent throughout. Inconsistencies would indicate the audio has been tampered with.

In the case of analogue audio, our analysts listen critically to the audio file in its entirety. We specifically listen for unfinished words, abnormal intonation and sentences that lack continuity and conversational flow, audio dropouts across the recording and examples of badly edited sections.

FVS are also able to identify reasons for audio dropout, including:

  • The copying method from the original exhibit
  • Badly set up equipment
  • Badly functioning equipment
  • Audio Authentication.
  • Audio transcripts of conversations.

Audio Transcripts

An expert ear is often essential to clearly understand what is going on. FVS can critically listen to a recording and produce a court-ready transcript of any English-language conversation.

We are also able to comment on the audibility and intelligibility of a recording:

If a voice cannot be heard then it is inaudible.

If a voice can be heard, but not understood, then it is unintelligible.


All FVS audio reports and transcriptions are independently peer-reviewed, and have been used to assist courts on a number of occasions.