Abstrakt
The expansion of telecommunication increased the availability of speech recordings which can be used in criminal investigations. Forensic science is a multidisciplinary approach that provides scientific grounds for assessing the evidence in such investigations.
Forensic phonetics explores segmental (vocalic, consonantal) and suprasegmental (prosodic) speech parameters that are discriminant among speakers. There is, however, a gap between technical data‑driven and linguistically informed approaches, which we attempt to bridge in this study by examining Czech vowels through rigorous computational means.
Seven different methods of quantifying vocalic spectral slope were compared for the purposes of speaker identification. In forensics, the use of spectral slope is mainly limited to the long‑term average spectra, which are easy to obtain, but have some serious drawbacks.
Therefore, in this study, short‑term spectra of Czech vowels were used: although their extraction is more laborious, they provide more speaker‑specific information. Of the seven methods tested, two software predefined functions performed unsatisfactorily, while a combination of modified band density difference and band density ratio was able to differentiate among all of our speakers.
The effect of vowel quality on these measures was also investigated.