2. Read the text and answer the following questions:

1. What is speaker identification and when is this method used?

2. How can forensic phoneticians help the investigation if the police haven’t found the suspect?

3. When is speaker profile requested?

4. What is tape analysis used for? Is it possible to prove that some sections of the tape have been excised or transposed? How?

5. What technique is used to eliminate the interference that disturbs a recording?

6. How can a forensic expert improve speech intelligibility on the tape?

7. What is a voice line-up? What purposes is it used for?

3. Make up a short summary of the text. Text 5

Read the text. Make up the plan for the text. What title would be the most suitable for it?

(Title)___________________________________

1.________________________________________________________

2.________________________________________________________

3.________________________________________________________

3.1._____________________________________________________

3.2._____________________________________________________

3.2.1. _______________________________________________

3.2.2.________________________________________________

3.2.3.________________________________________________

Perhaps somewhere between 70 percent and 80 percent of all forensic cases involve method of speaker identification (SID): that is, identifying a person who spoke in a criminal recording by means of comparative phonetic testing. A ‘criminal recording’ in this context may be anything from a hoax bomb warning recorded over an emergency telephone line, to a death threat left on a tape posted through the victim’s letterbox, or a surveillance recording made secretly by the police within the home of someone planning a robbery.

The commonest scenario for a forensic phonetician is to compare the questioned voice in the criminal recording with a speech sample from the suspect, in order to assess if it belongs to the same person. There was the case of a New Yorker accused of making threatening calls to Pan Am airlines. Detailed phonetic transcripts which compared the caller with the accused suggested beyond reasonable doubt that the caller was in fact from Boston, resulting in the acquittal of the accused. It is now widely accepted that there is no constant feature of an individual’s voice. That is, there is no vocal equivalent of a fingerprint or a DNA profile, which can offer irrefutable proof of speaker identity.

Research in sociolinguistics and phonetics has shown that an individual’s speech may vary as a result of many factors, including social and regional background. Speech features may also vary from situation to situation: for example, as a result of stress or the effect of speaking on a telephone. Different voices may also be affected in different ways. For instance, most people, but not all, speak more loudly when using a telephone, which results in a rise in average fundamental frequency.

There are several methods of speaker identification. The first and oldest form of speaker identification is of course speaker identification by ear-witnesses. The second major category comprises all forms of speaker identification by experts. At present, experts working in the field of forensic speaker identification use one of three approaches: (i) a phonetic-acoustic approach, (ii) a (semi-)automatic, analytical acoustic approach which is frequently combined with an auditory phonetic analysis, and (iii) a global automatic approach. Also methods are employed in which elements of the three types are combined in various ways.

Procedures of speaker identification by witnesses for evidential purposes typically involve the use of voice line-ups, following existing practice of visual identification of persons by witnesses. This consists of a set of recorded voices, including that of the suspect. It is widely assumed that recall of familiar voices is straightforward or even automatic. However, while it is generally true that recall of familiar voices is better than that of unfamiliar ones, even close friends and family members can show a significant degree of inaccuracy or inability to recognize voices that are well known to them. It has also been demonstrated that memory of a voice tends to decay over time, so that it is imperative to begin constructing a line-up test as soon as possible after the witnessing of the event. In practice, though, there may be long delays as a result of failure to apprehend a suspect quickly. That’s why nowadays this method is mainly used to confirm an earlier identification, as there is a great chance of false identification, which may lead to the conviction of an innocent person.

The second and probably most frequently practiced form in the forensic context is speaker identification by experts. Basically, all forensic phoneticians can be divided into three groups. The first group consists of trained phoneticians. They rely primarily on a combination of auditory phonetic analysis and a variety of acoustic measurements, and will generally only consider themselves competent to analyze speech samples in their own native language. The second group consists of those who use a set of semi-automatic measurements of particular acoustic speech parameters, for example vowel formants, and sometimes combine it with the results of a detailed, largely auditory phonetic analysis. The third, most recent approach differs from the first two in that it is both automatic and global. It is automatic in the sense that any subjective analysis or evaluation of the speech material is reduced to a minimum; it is global in the sense that it does not address specific acoustic speech parameters but treats the signal as a physical phenomenon.