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To be qualified as experts in voiceprint analysis, technicians
must:
- complete a course of study on spectrographic analysis that
generally runs from two to four weeks
- complete one hundred voice comparison cases under intense
personal supervision by a known expert
- be examined by a board of experts in the field
Since courts generally contest the methods of interpretation, not
the actual accuracy or reliability of the spectrographic instrument,
it is important that any spectrograph technician who testifies in
court be highly qualified. The less training and experience
the technician has, the more such testimony becomes vulnerable to
serious questions by the judge and jury.
All of the studies that have been done on spectrographic
accuracy, including a 1986 FBI survey, show that those people who
have been properly trained and who use standard aural and visual
procedures get highly accurate results. The opposite is true
where training and/or analysis methods are limited. Bringing
such studies to the attention of the courts could help determine who
is indeed an expert and could minimize some of the controversy and
confusion that comes from misperception.
Those who do the recordings for analysis must also be competent
to operate the recording device, because the quality of the tape has
great bearing on the interpreter's results.
The skills involved in aural and visual voice interpretation
include:
- Critical listening, with an ear for anomalies and the ability
to audit foreground information as distinguishable from
background
- Ability to check for tape tampering
- Experience reading magnetic tapes
- Ability to operate the spectrograph equipment, both for
general results and for zooming in on specific patterns
- Ability to work with an investigative team
In all likelihood, voiceprints will continue to play a key role
in any investigation that involves voice evidence. As such,
they will become part of the evidence brought into court. Like
other technologies that once were resisted but are now fully
admissible, voiceprints may soon have their day.
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