Measuring the impact of data size on the speaker discriminatory performance: a spontaneous speech-based study

This study aimed to analyze the impact of the amount of data on the discriminatory performance of acoustic-phonetic parameters, some of which are frequently assessed in forensic speaker comparisons. Parameters from three distinct phonetic domains were considered, namely, spectral, melodic, and temporal, which were assessed separately within the same phonetic domain and in combination. The speech material consisted of spontaneous telephone conversations between two subjects. During the recording sessions, the participants were placed in different rooms, not directly seeing, hearing, or interacting with each other. The speakers were encouraged to start a conversation using a mobile phone while being simultaneously recorded. All recordings were carried out with a high resolution (44.1 kHz and 16-bit). Data segmentation and transcription were performed in the Praat software [1]. The participants were 20 male subjects, Brazilian Portuguese speakers from the same dialectal area. Their age ranged from 19 to 35 years, with a mean of 26.4 years. Although the subjects (10 identical twin pairs) were recruited from a twin research project, cf. [2, 3, 4], the focus here was comparisons among all speakers (i.e., 190 inter-speaker comparisons) rather than on individual twin pair