Audio Forensic

Computer Forensics

Describe definitions of audio forensic Describe roles of audio forensic investigator Investigate and discuss sample of case

study related to audio forensic

2

Audio forensics is, the use of scientific investigation, technology

and tools to determine the authenticity of sound for civil or

criminal cases.

3

The results of audio forensics can be used as evidence in various legal cases dealing with anything from divorce to industrial espionage.

It's also not uncommon to see audio forensic analysis applied to surveillance tapes used in cases against employers or employees of a particular business.

4

Audio forensics has a long history with the United States military and government.

In World War II, the technology was used to identify the voices of targeted enemies that sounded over radios and telephones.

5

The use of a sound spectrograph, which plotted voice patterns' frequencies and amplitudes, helped analyzers identify people of interest.

In recent years, audio forensics is used to analyze messages created by terrorists to help pinpoint their locations, the audio's creation time and other originating factors.

6

Some of the things that are commonly evaluated in an audio clip to determine its authenticity are

◦ background noises, ◦ voice frequency changes, ◦ noises emanating from recording equipment and ◦ stop, start and pause signatures.

7

Any discontinuity in these areas may signal to the analyzer that the recording is inauthentic or has been compromised.

Sometimes, these discontinuities can be masked behind background sounds and extra work has to be done to uncover them.

8

One of the most popular techniques used during analysis is to compare one unknown sound against a known one to identify it.

This can be done in cases involving voices, where one speaker has been identified but the other has not.

9

With voices, vowel formant trajectory, pitch striations, breath patterns, speech pathologies and more can be used to identify speakers.

However, voice identification is still a complex and controversial issue

10

Many find that identification and recognition in forensics analysis unsuitable for court submission because of

◦ lacking in credibility◦ Issue of probability

11

TAPE ENHANCEMENT◦ Digital and analogue processing to restore verbal

clarity ◦ and make tapes easier to understand in a

courtroom situation.

12

AUTHENTICITY◦ Electronic and physical microscopic examination

of a tape ◦ to prove that it has not been tampered with,

altered, or otherwise changed from its original state.

◦ Another common authenticity challenge is to determine whether a given was tape was indeed made on a given machine.

13

VOICE IDENTIFICATION◦ Voice ID, or voice printing, is the science

that attempts to determine what was said, and by whom.

◦ A variety of analogue and digital analysis processes are used to analyze the frequency and amplitude characteristics of a human voice and compare it against known samples.

= make a sample of suspect voice and compare with the evidence voice to identify owner of the voice

14

Audio forensic investigation carried out need to follow SOP

Example of Common SOP1. Investigation must be done so that it adheres to

the standards of evidence and so it is admissible in a court of law.

2. Investigation must follow the proper Chain of Custody with that evidence.

15

Example of Common SOP3. Special precautions must be taken to ensure

that the evidence is properly protected and stored.

4. Considerations for peer review of casework should be made.

5. Ongoing training should be included and planned through professional organizations such as American Academy of Forensic Science and vendor specific training.

16

17

DAC QuickEnhance/AS v2.1◦ Enhancement◦ Please refer to Handout 1

Batvox◦ Voice identification/recognition◦ Please refer to Handout 2

Please refer to Handout 3 In a team,

◦ Summarize the incident◦ Describe how audio forensic fits-in in any

computer forensic cases◦ Explain what is the common objectives of audio

forensic investigations

18