Originality and interest

The application of the study of idiolectal style to forensic linguistics is fundamental since this application will allow linguists acting as expert witness in court to identify speakers or writers more reliably by comparing linguistic traits occurring in a disputed recording or written text and those occurring in a set of non-disputed spoken or written texts. While at present there is no such linguistic model which would account for all forensic needs, this projects seeks to answer a number of key questions involved in forensic linguistic analysis. The results obtained through the execution of this project could be used in real cases where linguistic expertise is needed in order to (among other actions):

• Identify speakers' voices and come up with linguistic profiles from voice recordings,
• Determine and attribute authorship of written texts such as suicide notes or threats, etc.,
• Detect plagiarism

The result of the application of the IIS to forensic real cases would also result in a better administration of justice.

Hypotheses

1. It is hypothesised that each individual has an idiolectal style which is unique and unreproduceable.
2. It is hypothesised that there will be more inter-speaker/writer than intra-speaker/
3. writer variation.
4. It is hypothesised that an individual’s idiolectal style will vary very slightly throughout time.
5. It is hypothesised that a speaker’s idiolectal style will not change much according to genre or context as regards their linguistic patterns (without considering vocabulary which can be, and usually is, constrained by register and genre).
6. Once, and if, these hypotheses are confirmed, it is hypothesised that it will be possible to establish an Index of Idiolectal Similitude, which could help experts in forensic voice comparison and authorship attribution contexts.

Main aims

1. To show that every speaker/writer makes use of his/her own idiolectal style, that is, a unique and idiosyncratic linguistic style, whose use is unconscious and which changes very slightly throughout time.
2. To apply the study of idiolectal style to forensic linguistics, since this application can help experts to identify producers of an oral text and writers of a written text more reliably.

Specific objectives

3. To undertake this application by comparing the linguistic forms/parameters used by speakers/writers in the production of disputed spoken or written texts and the linguistic forms/parameters used in a set of non-disputed spoken or written texts and   thus confirm that there exists more inter-speaker/writer than intra-speaker/writer  variation.
4. To undertake such application by using two measurements times, MT1 and MT2, in order to confirm that an individual's idiolectal style varies very slightly throughout time.
5. To measure the linguistic differences between several idiolectal styles and each individual’s  idiolectal distance so that an Index of Idiolectal Similitude can be obtained. More  specifically, it is a question of being able to establish what kind of idiolectal similitude  one needs to have before one can say that two linguistic samples (spoken or written)  have been produced by the same person.
6. To devise a protocol for the setting up of the aforementioned index which will compare several linguistic samples calculate the linguistic distance between them and help expert witnesses to decide whether or not two recordings or  two written texts have been produced by the same person.