Editing Voice analysis (section)

==Use in forensics==

Voice analysis is used in a branch of [[forensic science]] called [[audio forensics]]. These analyses are generally performed on evidence for the purposes of evaluating the authenticity of the audio in question, enhancing features of the audio that may be hidden beneath distracting background noise, interpreting the audio from the perspective of a forensic expert,<ref>Maher, Robert C. (2018). ''Principles of Forensic Audio Analysis''. Modern Acoustics and Signal Processing. Cham: Springer International Publishing. pp. 1–2. [[Doi (identifier)|doi]]:10.1007/978-3-319-99453-6. {{ISBN|978-3-319-99452-9}}.</ref> or in some cases for the purposes of [[speaker identification]].<ref>{{Cite book|last1=Solan|first1=Lawrence M.|title=Speaking of Crime|last2=Tiersma|first2=Peter M.|date=2004|publisher=University of Chicago Press|doi=10.7208/chicago/9780226767871.001.0001|isbn=978-0-226-76793-2}}</ref>

An expert will employ a variety of techniques in their analysis. The minimum of procedures are "critical listening, [[waveform]] analysis, and [[Spectrum analyzer#Audio frequency uses|spectral analysis]]".<ref name=":0">Maher, Robert C. (2018). ''Principles of Forensic Audio Analysis''. Modern Acoustics and Signal Processing. Cham: Springer International Publishing. pp. 48–49. [[Doi (identifier)|doi]]:10.1007/978-3-319-99453-6. {{ISBN|978-3-319-99452-9}}.</ref> Critical listening involves a thorough breakdown of both foreground and background sounds through repetitive listening.<ref name=":0" /> Waveform analysis visualizes the audio for the examiner to see any irregularities that may occur. Spectral analysis visualizes the frequency of the audio for an examiner to pick out features of interest.<ref name=":0" />

One case in which audio played a larger role is the [[Trial of George Zimmerman|Trayvon Martin case]], where a recording of a call made to the police was analyzed to determine if background screams came from [[George Zimmerman]] or from [[Trayvon Martin|Martin]].

=== Forensic Voice ===
Experts in forensic voice analyze recordings by examining transmitted and stored speech, enhancing it and decoding it for criminal investigations, court trials, and federal agencies.

To utilize audio recordings in court, a forensic phonetician must authenticate the recording to detect tampering, enhance the audio, and interpret the speech. Their first job is to ensure that the speech in the recording being used is comprehensible. Oftentimes, samples have poor sound quality due to environmental factors such as wind or movement. Other times the sound degradation is due to technological issues within the recording device. Any investigative work on speaker identification cannot be done until the recording is of proper quality. Different solutions for poor comprehensibility are done using computer programs that allow the user to filter and eliminate noise. Computer software is also able to convert the speech to spectra and waveforms, which is useful for the forensic phonetician. However, any work done on the recording should be done after a copy of the original recording is made.

A main part of the forensic phonetician's job is speaker identification. The interpretation process might include piecing together a timeline, transcribing the dialog, and identifying unknown or unintelligible sounds in the audio recording. In court, the expert ultimately serves to explain the facts surrounding the audio evidence, providing an explanation of relevant acoustical and physical principles to explain what is evidenced by the recording. Reports are made to include detailed information, if there is a section of the recording that is not comprehensible or is inaudible, an explanation of what was happening (in the recording), and a description of what is missing from the recording.

=== Speaker Identification ===
Voice analysis has a role in [[Speaker recognition|speaker identification]]. This is when the identity of a speaker is unknown, and has to be identify from an array of other voices or suspects when pertaining to a crime investigation or court trial.  Proper identification of speaker and voices particularly for criminal cases depend on a list of factors, like familiarity, exposure, delay, tone of voice, voice disguising, and accents. Familiarity with a speaker increases the chances of properly identifying a voice, and distinguishing it. The amount of exposure to a voice also aids in correctly identifying a voice, even if it is an unfamiliar one. A hearer that listen to a longer utterance or was exposed to a voice more often is better at recognizing a voice, than someone who perhaps was only able to hear one word. A delay between the time of hearing a voice and the time of identifying the speaker also decreases the prospect of identifying the correct speaker. The [[Tone (linguistics)|tone of voice]] affects the ability to identify the right speaker. If the tone does not match that of the speaker at the time of comparison, it will prove to be more difficult to analyse. Disguise of the voice, for example when a speaker is whispering, will also hinder the ability to accurately match and identify the speaker. In some cases, individuals who speak the same language as the speaker whose voice is being analysed will have an easier time identifying them because of the [[Stress (linguistics)|accent and stress]] of the voice. Speaker identification is additionally complicated by distortions from the technical method of recording and speaker based issues, such as emotional states or alternative motives causing a discrepancy between their voice and that of a recording. The methods of speaker identification in forensics include the use of earwitnesses who are used to identify voices they have heard, the aural-perceptual approach conducted by a specialist regarding the suprasegmentals of an individual's speech, and computer-based approaches.