This dissertation investigates the relationship between linguistic factors and speaker-dependent information in speech sounds, with a particular focus on the Dutch language and on fricative and... Show moreThis dissertation investigates the relationship between linguistic factors and speaker-dependent information in speech sounds, with a particular focus on the Dutch language and on fricative and nasal consonants. Using spontaneous telephone speech corpora, this work provides an empirical contribution to forensic speech science by aiming to answer the question of whether acoustic-phonetic features from consonants should be extracted from and compared across different linguistic environments, also considering the recording condition.This thesis reports the results of a number of studies on the sources of variation in consonant acoustics. First, it analyses the role of phonetic context and syllabic position for speaker variation that is present in fricative and nasal consonants, which have previously been shown to be useful sounds in forensic speaker comparisons. Second, the interactions between linguistic effects and recording conditions (telephone versus microphone) are investigated. Finally, forensic strength-of-evidence was derived using Bayesian likelihood-ratio modelling to determine the practical consequences of these findings to forensic speaker comparisons. Show less
Filled pauses are widely considered as a relatively consistent feature of an individual’s speech. However, acoustic consistency has only been observed within single-session recordings. By comparing... Show moreFilled pauses are widely considered as a relatively consistent feature of an individual’s speech. However, acoustic consistency has only been observed within single-session recordings. By comparing filled pauses in two recordings made >2.5 years apart, this study investigates within-speaker consistency of the vowels in the filled pauses uh and um, in both first language (L1) Dutch and second language (L2) English, produced by student speakers who are known to converge in other speech features. Results show that despite minor within-speaker differences between languages, the spectral characteristics of filled pauses in L1 and L2 remained stable over time. Show less
Identifying speakers by their spoken output is a specialist task for forensic investigators. In the present study we focused on cross-linguistic speaker (Chinese, English, Dutch) identification... Show moreIdentifying speakers by their spoken output is a specialist task for forensic investigators. In the present study we focused on cross-linguistic speaker (Chinese, English, Dutch) identification based on (components of) English stops and fricatives, /p, b, t, d, k, g/ and the fricatives /f, v, θ, ð, s, z, ʃ, ʒ/. English noise bursts’ contribution to native language identification is presented and the special tokens which contribute the most were analyzed. Show less
