An investigator discovers new digital audio in relation to an open murder investigation. It contains the confession of what they believe to be their top current suspect. In order to determine whether the voice in question is a match for their suspect’s and use the evidence as an ear-witness, the investigator sends the audio to an audio analysis expert through the following steps:
- An investigator receives new digital audio evidence. They create a backup and store the following information about the file:
- File Name
- File Hash
- Audio Length
- Associated Provenance Record
- Recording Device Information
- The investigator zips the files up and records the time/date along with the hash and sends them to the audio expert to perform analysis.
- The Audio Forensics Expert (AFE) loads the received file onto a forensic computer. They perform initial checks to get baselines as well as to ensure the file has not been doctored/modified. This is done by looking at factors such as ambient sound to make sure it is consistent.
- The AFE procures the exact model of the recording device originally used to gather the evidence and attempts to configure similar settings to the original recording based on their baselines.
- The AFE works with the investigator to create an exemplar of the accused suspect for audio comparison by having the accused say a combination of single words as well as phrases and sentences.
- The AFE, having collected all required data for analysis, finally analyzes the audio using different tools to analyze and compare sound waves and sonogram information as well as the delivery of speech, documenting all tools used.
- The AFE sends back a report to the investigator containing whether they believe the audio evidence to be a match.