Voice comparison is one of the most frequently addressed terms in the context of forensic phonetics; however, so far experts have not been able to find a speech parameter which reliably discriminates between two speakers. Formant dynamics have brought promising results in this respect, therefore in our study using linear discriminant analysis (LDA) we tested the speaker-discriminatory potential of formant trajectories on real forensic recordings. The aim was firstly, to compare the results of LDA when formant frequencies or coefficients of quadratic and cubic fit are used as predictors and secondly, to compare the results when the analyzed classes are balanced or not regarding the number of objects. As for the predictors, all of the types demonstrated comparable classification rates, nevertheless, as LDA limits the number of predictors in relation to the class size, the quadratic fit appears to be the most efficient. Even though LDA was able to discriminate between different voices above chance, it cannot be recommended for forensic use. It delivered highly inconsistent results when the number of objects in the classes was changed; and more importantly, it significantly discriminates between objects of the same speaker. Key words: formant trajectories, voice comparison, LDA, Czech, forensic phonetics
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:369975 |
| Date | January 2017 |
| Creators | Nechanský, Tomáš |
| Contributors | Skarnitzl, Radek, Veroňková, Jitka |
| Source Sets | Czech ETDs |
| Language | Czech |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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