depend partly on your actual auditory memory for
voices and partly on your expectations of who might be
calling you, your knowledge of people who know your
phone number, and even considerations such as the
time of day. And almost all of us have had the experi-
ence of picking up the telephone, expecting a particular
caller, “identifying” the voice as that of a friend or rel-
ative, only to realize minutes later that the caller is actu-
ally a stranger who has dialed a wrong number.
In a typical earwitness experiment, participants lis-
ten to a recorded statement of a particular duration and
may or may not be informed that they will be asked to
recognize the voice later. After a period of time, the par-
ticipants are exposed to a voice lineup consisting of
several different voices and are asked to choose the
voice that had uttered the original statement.
Participants also often rate their confidence in their
choice or are asked whether they are certain enough to
testify in court regarding their identification. In a study
by Daniel Read and Fergus Craik, for example, college
students heard a series of statements, including a male
target voice saying, “Help me, help me, oh God, help
me!” (the words heard by Christine Jessop’s mother)
and were asked to rate the emotionality of each state-
ment. They did not know that they would be asked to
recognize any of the voices in the future. At a class
meeting 17 days later, the same students were asked to
listen to a series of 20-second, conversational utter-
ances by 6 male speakers and to choose the one that had
uttered the statement in question. The target voice was
one of the voices in the lineup. Pure guessing would
have resulted in a chance performance level of 17%
(1 out of 6). In fact, the accuracy of the students in the
study was only 20% correct, no better than chance.
Most studies also incorporate a “target-absent”
lineup to measure the likelihood of a false identification
when the lineup does not contain the actual perpetrator.
Such research points out the danger of misidentifying
an unfamiliar voice as familiar; even with a relatively
lengthy exposure to a distinctive target voice, false
identification rates in such a target-absent lineup can be
as high as 90% to 100%.Factors Influencing Voice
Recognition Accuracy
The likelihood of correctly identifying a voice depends on
a number of factors or estimator variables, many of
which also influence eyewitness accuracy. Limited expo-
sure to a voice can lead to decreased accuracy; the longer
the time that the perpetrator spends talking, the morelikely the witness is to properly encode the voice charac-
teristics. It is important to recognize, however, that wit-
nesses are likely to overestimate the length of time that
the perpetrator spent speaking. A 30-second speech sam-
ple, for example, is typically remembered as having
lasted from 90 seconds to more than 2 minutes. The
amount of time that passes between initially hearing a
voice and then being tested for recognition is also critical.
The longer the delay between exposure and testing, the
greater the chance of error becomes, particularly errors in
the form of false recognitions of innocent persons’ voices.
Background noise can interfere with the witness’s ability
to encode voice characteristics. The proximity of the wit-
ness to the speaker is also important, with closer proxim-
ity being associated with greater accuracy.
The ability to see a perpetrator’s face may also
adversely affect the recognition of the perpetrator’s
voice, a phenomenon known as the face overshadowing
effect. It is thought that a witness pays relatively more
attention to the face when it is visible, resulting in
decreased voice identification accuracy. Studies have
shown, however, that instructions to pay attention to the
voice do not significantly reduce the face overshadow-
ing effect, suggesting a process that may not be under
the witness’s conscious control. Use of voice recogni-
tion evidence in situations where the perpetrator’s face
has been visible, then, is considered unreliable.
Studies of eyewitness identification consistently find
superior performance in recognizing faces of one’s own
race as opposed to faces of another race. There is a sim-
ilar finding in voice recognition research regarding
accents and languages. English speakers, for example,
have been shown to be more accurate in recognizing
unaccented English-speaking voices than heavily
accented English-speaking voices and least accurate in
recognizing voices speaking in a foreign language.
Language familiarity, then, has a significant positive
effect on voice identification accuracy. (Gender, on the
other hand, has no consistent relationship to voice
recognition.)
Stress can also decrease the accuracy of voice recog-
nition. When viewing videotaped crimes in the labora-
tory, research participants typically make more errors in
both face and voice recognition when violent threats
are made or a weapon is present. Our ability to pay
attention to all aspects of our surroundings is limited
under any circumstances, and under conditions of stress
it becomes more limited. When threats are made, it is
more important to our survival to listen to and remem-
ber the content of the spoken message rather than the
vocal qualities of the speaker.Voice Recognition——— 853V-Cutler (Encyc)-45463.qxd 11/18/2007 12:44 PM Page 853