A test of the effectiveness of speaker verification for differentiating between identical twins

ABSTRACT This paper presents investigations into the ability of speaker verification technology to discriminate between identical twins. It is shown that whilst, in general, the genetic and non-genetic characteristics of voice are both of value to speaker verification capabilities, it is the latter which is highly beneficial in the separation of the speech of identical twins. It is further demonstrated that through the use of unconstrained cohort normalisation as a complementary means for the exploitation of such voice characteristics, the verification reliability can be considerably enhanced for both identical twins and unrelated speakers. Experiments were conducted using a bespoke clean-speech database consisting of utterances from forty nine identical twin pairs. The paper details the problem in speaker verification posed by identical twins, discusses the experimental investigations and provides an analysis of the results

Evaluating the forensic importance of glottal source features through the voice analysis of twins and non-twin siblings

In this study we have analyzed 853 tokens of the vowel filler [ei], extracted from spontaneous speech fragments of 54 male Spanish speakers (NorthCentral Peninsular variety), each one recorded on two separate sessions. The speakers — to be compared in a pairwise fashion - were divided in four groups: 24 monozygotic (MZ) twins, 10 dizygotic (DZ) twins, 8 non-twin brothers and 12 unrelated speakers. From the extracted vowel fillers, considered long enough for a glottal analysis (around 160 milliseconds), a vector of 68 glottal parameters was created. Our hypothesis that higher similarity values would be found in the intra-pair comparison ofMZ twins than in DZ twins, brothers or unrelated speakers was confirmed, which suggests that the glottal parameters under investigation are genetically influenced. This finding seems of great forensic importance, as a phonetic parameter is considered forensically robust provided that it exhibits large between-speaker variation while it remains as consistent as possible for each speaker (i.e. small within-speaker variation)

Reconocimiento automático de locutor con hermanos españoles: hermanos gemelos (monozigóticos y dizigóticos) y no gemelos

The performance of the automatic speaker recognition (ASR) system BatvoxTM (Version 4.1) has been tested with a male population of 24 monozygotic (MZ) twins, 10 dizygotic (DZ) twins, 8 non-twin siblings and 12 unrelated speakers (aged 18–52 with Standard Peninsular Spanish as their mother tongue). Since the cepstral features in which this ASR system is based depend largely on anatomical–physiological foundations, we hypothesized that such features ought to be gene-dependent. Therefore, higher similarity values should be found in MZ twins (100% shared genes) than in DZ twins, in brothers (B) or in a reference population of unrelated speakers (US). Results corroborated the expected decreasing scale MZ > DZ > B > US since the similarity coefficients yielded by the automatic system for these speakers decreased exactly in the same direction as the kinship degree of the four speaker groups diminishes. This suggests that the system features are to a great extent genetically conditioned and that they are hence useful and robust for comparing speech samples of known and unknown origin, as found in legal cases. Furthermore, the 9.9% EER (Equal Error Rate) obtained when testing MZ pairs lies around the same value (11% EER) found in Künzel (2010) with German twins.Hemos utilizado el sistema de reconocimiento automático BatvoxTM (versión 4.1) con una población de hablantes masculinos compuesta de 24 gemelos monocigóticos, 10 gemelos dicigóticos, 8 hermanos no gemelares y 12 hablantes no emparentados (edades comprendidas entre 18 y 52 años, con español centropeninsular como lengua materna). Puesto que los parámetros cepstrales en los que se basa BatvoxTM dependen en gran medida de las bases anatómicas y fisiológicas del tracto vocal del hablante, se propuso que estos debían estar influenciados genéticamente. Esta hipótesis se pudo corroborar, puesto que los coeficientes de similitud arrojados por el sistema automático decrecen exactamente en la misma dirección en la que disminuye el grado de parentesco de las parejas de hablantes, es decir: gemelos monocigóticos, dicigóticos, hermanos no gemelares y hablantes no emparentados. Esto es, los gemelos monocigóticos obtuvieron valores más altos que los dicigóticos; estos, a su vez, mayores que los hermanos no gemelares, y, finalmente, estos últimos mayores que los hablantes no emparentados. Estos resultados sugieren que los parámetros en los que está basado este sistema de reconocimiento están condicionados en gran medida por aspectos genéticos y, por tanto, resultan útiles y robustos para la comparación de muestras de voz dubitadas e indubitadas que encontramos en un caso típicamente forense. Por otro lado, el EER (Equal Error Rate) del 9 % que se obtuvo en las comparaciones exclusivamente de gemelos monocigóticos supone un valor muy similar al hallado en estudios anteriores con gemelos monocigóticos alemanes, como Künzel (2010): EER del 11 %

Euclidean distances as measures of speaker similarity including identical twin pairs: a forensic investigation using source and filter voice characteristics

AbstractThere is a growing consensus that hybrid approaches are necessary for successful speaker characterization in Forensic Speaker Comparison (FSC); hence this study explores the forensic potential of voice features combining source and filter characteristics. The former relate to the action of the vocal folds while the latter reflect the geometry of the speaker’s vocal tract. This set of features have been extracted from pause fillers, which are long enough for robust feature estimation while spontaneous enough to be extracted from voice samples in real forensic casework. Speaker similarity was measured using standardized Euclidean Distances (ED) between pairs of speakers: 54 different-speaker (DS) comparisons, 54 same-speaker (SS) comparisons and 12 comparisons between monozygotic twins (MZ). Results revealed that the differences between DS and SS comparisons were significant in both high quality and telephone-filtered recordings, with no false rejections and limited false acceptances; this finding suggests that this set of voice features is highly speaker-dependent and therefore forensically useful. Mean ED for MZ pairs lies between the average ED for SS comparisons and DS comparisons, as expected according to the literature on twin voices. Specific cases of MZ speakers with very high ED (i.e. strong dissimilarity) are discussed in the context of sociophonetic and twin studies. A preliminary simplification of the Vocal Profile Analysis (VPA) Scheme is proposed, which enables the quantification of voice quality features in the perceptual assessment of speaker similarity, and allows for the calculation of perceptual–acoustic correlations. The adequacy of z-score normalization for this study is also discussed, as well as the relevance of heat maps for detecting the so-called phantoms in recent approaches to the biometric menagerie

Individual Differences in Speech Production and Perception

Inter-individual variation in speech is a topic of increasing interest both in human sciences and speech technology. It can yield important insights into biological, cognitive, communicative, and social aspects of language. Written by specialists in psycholinguistics, phonetics, speech development, speech perception and speech technology, this volume presents experimental and modeling studies that provide the reader with a deep understanding of interspeaker variability and its role in speech processing, speech development, and interspeaker interactions. It discusses how theoretical models take into account individual behavior, explains why interspeaker variability enriches speech communication, and summarizes the limitations of the use of speaker information in forensics

Models and Analysis of Vocal Emissions for Biomedical Applications

The MAVEBA Workshop proceedings, held on a biannual basis, collect the scientific papers presented both as oral and poster contributions, during the conference. The main subjects are: development of theoretical and mechanical models as an aid to the study of main phonatory dysfunctions, as well as the biomedical engineering methods for the analysis of voice signals and images, as a support to clinical diagnosis and classification of vocal pathologies

Multimodal biometrics scheme based on discretized eigen feature fusion for identical twins identification

The subject of twins multimodal biometrics identification (TMBI) has consistently been an interesting and also a valuable area of study. Considering high dependency and acceptance, TMBI greatly contributes to the domain of twins identification in biometrics traits. The variation of features resulting from the process of multimodal biometrics feature extraction determines the distinctive characteristics possessed by a twin. However, these features are deemed as inessential as they cause the increase in the search space size and also the difficulty in the generalization process. In this regard, the key challenge is to single out features that are deemed most salient with the ability to accurately recognize the twins using multimodal biometrics. In identification of twins, effective designs of methodology and fusion process are important in assuring its success. These processes could be used in the management and integration of vital information including highly selective biometrics characteristic possessed by any of the twins. In the multimodal biometrics twins identification domain, exemplification of the best features from multiple traits of twins and biometrics fusion process remain to be completely resolved. This research attempts to design a new scheme and more effective multimodal biometrics twins identification by introducing the Dis-Eigen feature-based fusion with the capacity in generating a uni-representation and distinctive features of numerous modalities of twins. First, Aspect United Moment Invariant (AUMI) was used as global feature in the extraction of features obtained from the twins handwritingfingerprint shape and style. Then, the feature-based fusion was examined in terms of its generalization. Next, to achieve better classification accuracy, the Dis-Eigen feature-based fusion algorithm was used. A total of eight distinctive classifiers were used in executing four different training and testing of environment settings. Accordingly, the most salient features of Dis-Eigen feature-based fusion were trained and tested to determine the accuracy of the classification, particularly in terms of performance. The results show that the identification of twins improved as the error of similarity for intra-class decreased while at the same time, the error of similarity for inter-class increased. Hence, with the application of diverse classifiers, the identification rate was improved reaching more than 93%. It can be concluded from the experimental outcomes that the proposed method using Receiver Operation Characteristics (ROC) considerably increases the twins handwriting-fingerprint identification process with 90.25% rate of identification when False Acceptance Rate (FAR) is at 0.01%. It is also indicated that 93.15% identification rate is achieved when FAR is at 0.5% and 98.69% when FAR is at 1.00%. The new proposed solution gives a promising alternative to twins identification application

Exploring the Pedagogical Potential of Contemporary Fantasy Literature for Promoting Critical Literacy in the EFL Classroom

This master’s thesis analyzes and discusses the potential of three contemporary fantasy novels, Children of Blood and Bone (2018), Skin of the Sea (2021), and Nevermoor (2017), for promoting critical literacy through the use of literature in EFL classrooms in Norway. The thesis argues for the importance of diverse, contemporary literature in classrooms to supplement the existing dominant perspectives. By introducing modern voices that represent different racial, cultural, and societal backgrounds, this research argues for more diverse, inclusive, and balanced representation in Norwegian classrooms. The fantasy genre serves as a starting point for this project because of its popularity with young readers and its potential as an avenue for exploring sociopolitical issues in the real world. The aim of this project is two-fold: first, to identify central themes and elements in the selected texts from a critical literacy perspective, and second, to examine how these texts can be used to nurture critical literacy among EFL learners. The thesis is based on the ideas of critical literacy theory, particularly Lewison et al.’s model of the four dimensions of critical literacy and Borsheim-Black et al.’s Critical Literature Pedagogy framework. The methodology involves a thematic literary analysis using elements from close reading and the CLP framework to unearth themes relevant to teaching critical literacy. The discussion chapter delves into analyzing the novels in regard to the dimensions in the CLP framework into the practical implications of integrating these novels into EFL instruction. The main findings of the thesis reveal that the texts deeply explore themes of power structures, systemic inequality and prejudice, and the implications of dominant versus marginalized narratives. These are integral aspects to both critical literacy and important topics to cover in the classroom in relation to the values of the LK20 curriculum, particularly in its aims of promoting inclusivity and diversity, counteracting prejudice, and encouraging critical thinking. This implies that these novels could have great potential both for teaching language skills and encouraging critical literacy in the Norwegian EFL classroom