Search

Your search keyword '"Hughes, Vincent"' showing total 121 results
Start Over Author "Hughes, Vincent"
121 results on '"Hughes, Vincent"'

7. The definition of the relevant population and the collection of data for likelihood ratio-based forensic voice comparison

Author

Hughes, Vincent and Foulkes, Paul

Subjects
400
Abstract

Within the field of forensic speech science there is increasing acceptance of the likelihood ratio (LR) as the logically and legally correct framework for evaluating forensic voice comparison (FVC) evidence. However, only a small proportion of experts currently use the numerical LR in casework. This is due primarily to the difficulties involved in accounting for the inherent, and arguably unique, complexity of speech in a fully data-driven, numerical LR analysis. This thesis addresses two such issues: the definition of the relevant population and the amount of data required for system testing. Firstly, experiments are presented which explore the extent to which LRs are affected by different definitions of the relevant population with regard to sources of systematic sociolinguistic between-speaker variation (regional background, socio-economic class and age) using both linguistic-phonetic and ASR variables. Results show that different definitions of the relevant population can have a substantial effect on the magnitude of LRs, depending on the input variable. However, system validity results suggest that narrow controls over sociolinguistic sources of variation should be preferred to general controls. Secondly, experiments are presented which evaluate the effects of development, test and reference sample size on LRs. Consistent with general principles in statistics, more precise results are found using more data across all experiments. There is also considerable evidence of a relationship between sample size sensitivity and the dimensionality and speaker discriminatory power of the input variable. Further, there are potential trade-offs in the size of each set depending on which element of LR output the analyst is interested in. The results in this thesis will contribute towards improving the extent to which LR methods account for the linguistic-phonetic complexity of speech evidence. In accounting for this complexity, this work will also increase the practical viability of applying the numerical LR to FVC casework.

Published
2014

11. Multidimensional Signals and Analytic Flexibility: Estimating Degrees of Freedom in Human-Speech Analyses

Author

Coretta, Stefano, primary, Casillas, Joseph V., additional, Roessig, Simon, additional, Franke, Michael, additional, Ahn, Byron, additional, Al-Hoorie, Ali H., additional, Al-Tamimi, Jalal, additional, Alotaibi, Najd E., additional, AlShakhori, Mohammed K., additional, Altmiller, Ruth M., additional, Arantes, Pablo, additional, Athanasopoulou, Angeliki, additional, Baese-Berk, Melissa M., additional, Bailey, George, additional, Sangma, Cheman Baira A, additional, Beier, Eleonora J., additional, Benavides, Gabriela M., additional, Benker, Nicole, additional, BensonMeyer, Emelia P., additional, Benway, Nina R., additional, Berry, Grant M., additional, Bing, Liwen, additional, Bjorndahl, Christina, additional, Bolyanatz, Mariška, additional, Braver, Aaron, additional, Brown, Violet A., additional, Brown, Alicia M., additional, Brugos, Alejna, additional, Buchanan, Erin M., additional, Butlin, Tanna, additional, Buxó-Lugo, Andrés, additional, Caillol, Coline, additional, Cangemi, Francesco, additional, Carignan, Christopher, additional, Carraturo, Sita, additional, Caudrelier, Tiphaine, additional, Chodroff, Eleanor, additional, Cohn, Michelle, additional, Cronenberg, Johanna, additional, Crouzet, Olivier, additional, Dagar, Erica L., additional, Dawson, Charlotte, additional, Diantoro, Carissa A., additional, Dokovova, Marie, additional, Drake, Shiloh, additional, Du, Fengting, additional, Dubuis, Margaux, additional, Duême, Florent, additional, Durward, Matthew, additional, Egurtzegi, Ander, additional, Elsherif, Mahmoud M., additional, Esser, Janina, additional, Ferragne, Emmanuel, additional, Ferreira, Fernanda, additional, Fink, Lauren K., additional, Finley, Sara, additional, Foster, Kurtis, additional, Foulkes, Paul, additional, Franzke, Rosa, additional, Frazer-McKee, Gabriel, additional, Fromont, Robert, additional, García, Christina, additional, Geller, Jason, additional, Grasso, Camille L., additional, Greca, Pia, additional, Grice, Martine, additional, Grose-Hodge, Magdalena S., additional, Gully, Amelia J., additional, Halfacre, Caitlin, additional, Hauser, Ivy, additional, Hay, Jen, additional, Haywood, Robert, additional, Hellmuth, Sam, additional, Hilger, Allison I., additional, Holliday, Nicole, additional, Hoogland, Damar, additional, Huang, Yaqian, additional, Hughes, Vincent, additional, Icardo Isasa, Ane, additional, Ilchovska, Zlatomira G., additional, Jeon, Hae-Sung, additional, Jones, Jacq, additional, Junges, Mágat N., additional, Kaefer, Stephanie, additional, Kaland, Constantijn, additional, Kelley, Matthew C., additional, Kelly, Niamh E., additional, Kettig, Thomas, additional, Khattab, Ghada, additional, Koolen, Ruud, additional, Krahmer, Emiel, additional, Krajewska, Dorota, additional, Krug, Andreas, additional, Kumar, Abhilasha A., additional, Lander, Anna, additional, Lentz, Tomas O., additional, Li, Wanyin, additional, Li, Yanyu, additional, Lialiou, Maria, additional, Lima, Ronaldo M., additional, Lo, Justin J. H., additional, Lopez Otero, Julio Cesar, additional, Mackay, Bradley, additional, MacLeod, Bethany, additional, Mallard, Mel, additional, McConnellogue, Carol-Ann Mary, additional, Moroz, George, additional, Murali, Mridhula, additional, Nalborczyk, Ladislas, additional, Nenadić, Filip, additional, Nieder, Jessica, additional, Nikolić, Dušan, additional, Nogueira, Francisco G. S., additional, Offerman, Heather M., additional, Passoni, Elisa, additional, Pélissier, Maud, additional, Perry, Scott J., additional, Pfiffner, Alexandra M., additional, Proctor, Michael, additional, Rhodes, Ryan, additional, Rodríguez, Nicole, additional, Roepke, Elizabeth, additional, Röer, Jan P., additional, Sbacco, Lucia, additional, Scarborough, Rebecca, additional, Schaeffler, Felix, additional, Schleef, Erik, additional, Schmitz, Dominic, additional, Shiryaev, Alexander, additional, Sóskuthy, Márton, additional, Spaniol, Malin, additional, Stanley, Joseph A., additional, Strickler, Alyssa, additional, Tavano, Alessandro, additional, Tomaschek, Fabian, additional, Tucker, Benjamin V., additional, Turnbull, Rory, additional, Ugwuanyi, Kingsley O., additional, Urrestarazu-Porta, Iñigo, additional, van de Vijver, Ruben, additional, Van Engen, Kristin J., additional, van Miltenburg, Emiel, additional, Wang, Bruce Xiao, additional, Warner, Natasha, additional, Wehrle, Simon, additional, Westerbeek, Hans, additional, Wiener, Seth, additional, Winters, Stephen, additional, Wong, Sidney G.-J., additional, Wood, Anna, additional, Wottawa, Jane, additional, Xu, Chenzi, additional, Zárate-Sández, Germán, additional, Zellou, Georgia, additional, Zhang, Cong, additional, Zhu, Jian, additional, and Roettger, Timo B., additional

Published
2023
Full Text
View/download PDF

13. Multidimensional Signals and Analytic Flexibility: Estimating Degrees of Freedom in Human-Speech Analyses

Author

Coretta, Stefano, Casillas, Joseph v., Roessig, Simon, Franke, Michael, Ahn, Byron, Al-Hoorie, Ali h., Al-Tamimi, Jalal, Alotaibi, Najd e., Alshakhori, Mohammed k., Altmiller, Ruth m., Arantes, Pablo, Athanasopoulou, Angeliki, Baese-Berk, Melissa m., Bailey, George, Sangma, Cheman baira a, Beier, Eleonora j., Benavides, Gabriela m., Benker, Nicole, Bensonmeyer, Emelia p., Benway, Nina r., Berry, Grant m., Bing, Liwen, Bjorndahl, Christina, Bolyanatz, Mariška, Braver, Aaron, Brown, Alicia m., Brugos, Alejna, Buchanan, Erin m., Butlin, Tanna, Buxó-Lugo, Andrés, Caillol, Coline, Cangemi, Francesco, Carignan, Christopher, Carraturo, Sita, Caudrelier, Tiphaine, Chodroff, Eleanor, Cohn, Michelle, Cronenberg, Johanna, Crouzet, Olivier, Dagar, Erica l., Dawson, Charlotte, Diantoro, Carissa a., Dokovova, Marie, Drake, Shiloh, Du, Fengting, Dubuis, Margaux, Duême, Florent, Durward, Matthew, Egurtzegi, Ander, Elsherif, Mahmoud m., Esser, Janina, Ferragne, Emmanuel, Ferreira, Fernanda, Fink, Lauren k., Finley, Sara, Foster, Kurtis, Foulkes, Paul, Franzke, Rosa, Frazer-Mckee, Gabriel, Fromont, Robert, García, Christina, Geller, Jason, Grasso, Camille l., Greca, Pia, Grice, Martine, Grose-Hodge, Magdalena s., Gully, Amelia j., Halfacre, Caitlin, Hauser, Ivy, Hay, Jen, Haywood, Robert, Hellmuth, Sam, Hilger, Allison i., Holliday, Nicole, Hoogland, Damar, Huang, Yaqian, Hughes, Vincent, Icardo isasa, Ane, Ilchovska, Zlatomira g., Jeon, Hae-Sung, Jones, Jacq, Junges, Mágat n., Kaefer, Stephanie, Kaland, Constantijn, Kelley, Matthew c., Kelly, Niamh e., Kettig, Thomas, Khattab, Ghada, Koolen, Ruud, Krahmer, Emiel, Krajewska, Dorota, Krug, Andreas, Kumar, Abhilasha a., Lander, Anna, Lentz, Tomas o., Li, Wanyin, Li, Yanyu, Lialiou, Maria, Lima, Ronaldo m., Lo, Justin j. h., Lopez otero, Julio cesar, Mackay, Bradley, Macleod, Bethany, Mallard, Mel, Mcconnellogue, Carol-Ann mary, Moroz, George, Murali, Mridhula, Nalborczyk, Ladislas, Nenadić, Filip, Nieder, Jessica, Nikolić, Dušan, Nogueira, Francisco g. s., Offerman, Heather m., Passoni, Elisa, Pélissier, Maud, Perry, Scott j., Pfiffner, Alexandra m., Proctor, Michael, Rhodes, Ryan, Rodríguez, Nicole, Roepke, Elizabeth, Röer, Jan p., Sbacco, Lucia, Scarborough, Rebecca, Schaeffler, Felix, Schleef, Erik, Schmitz, Dominic, Shiryaev, Alexander, Sóskuthy, Márton, Spaniol, Malin, Stanley, Joseph a., Strickler, Alyssa, Tavano, Alessandro, Tomaschek, Fabian, Tucker, Benjamin v., Turnbull, Rory, Ugwuanyi, Kingsley o., Urrestarazu-Porta, Iñigo, Van de vijver, Ruben, Van engen, Kristin j., Van miltenburg, Emiel, Wang, Bruce xiao, Warner, Natasha, Wehrle, Simon, Westerbeek, Hans, Wiener, Seth, Winters, Stephen, Wong, Sidney g.-J., Wood, Anna, Wottawa, Jane, Xu, Chenzi, Zárate-Sández, Germán, Zellou, Georgia, Zhang, Cong, Zhu, Jian, Roettger, Timo b., Coretta, Stefano, Casillas, Joseph v., Roessig, Simon, Franke, Michael, Ahn, Byron, Al-Hoorie, Ali h., Al-Tamimi, Jalal, Alotaibi, Najd e., Alshakhori, Mohammed k., Altmiller, Ruth m., Arantes, Pablo, Athanasopoulou, Angeliki, Baese-Berk, Melissa m., Bailey, George, Sangma, Cheman baira a, Beier, Eleonora j., Benavides, Gabriela m., Benker, Nicole, Bensonmeyer, Emelia p., Benway, Nina r., Berry, Grant m., Bing, Liwen, Bjorndahl, Christina, Bolyanatz, Mariška, Braver, Aaron, Brown, Alicia m., Brugos, Alejna, Buchanan, Erin m., Butlin, Tanna, Buxó-Lugo, Andrés, Caillol, Coline, Cangemi, Francesco, Carignan, Christopher, Carraturo, Sita, Caudrelier, Tiphaine, Chodroff, Eleanor, Cohn, Michelle, Cronenberg, Johanna, Crouzet, Olivier, Dagar, Erica l., Dawson, Charlotte, Diantoro, Carissa a., Dokovova, Marie, Drake, Shiloh, Du, Fengting, Dubuis, Margaux, Duême, Florent, Durward, Matthew, Egurtzegi, Ander, Elsherif, Mahmoud m., Esser, Janina, Ferragne, Emmanuel, Ferreira, Fernanda, Fink, Lauren k., Finley, Sara, Foster, Kurtis, Foulkes, Paul, Franzke, Rosa, Frazer-Mckee, Gabriel, Fromont, Robert, García, Christina, Geller, Jason, Grasso, Camille l., Greca, Pia, Grice, Martine, Grose-Hodge, Magdalena s., Gully, Amelia j., Halfacre, Caitlin, Hauser, Ivy, Hay, Jen, Haywood, Robert, Hellmuth, Sam, Hilger, Allison i., Holliday, Nicole, Hoogland, Damar, Huang, Yaqian, Hughes, Vincent, Icardo isasa, Ane, Ilchovska, Zlatomira g., Jeon, Hae-Sung, Jones, Jacq, Junges, Mágat n., Kaefer, Stephanie, Kaland, Constantijn, Kelley, Matthew c., Kelly, Niamh e., Kettig, Thomas, Khattab, Ghada, Koolen, Ruud, Krahmer, Emiel, Krajewska, Dorota, Krug, Andreas, Kumar, Abhilasha a., Lander, Anna, Lentz, Tomas o., Li, Wanyin, Li, Yanyu, Lialiou, Maria, Lima, Ronaldo m., Lo, Justin j. h., Lopez otero, Julio cesar, Mackay, Bradley, Macleod, Bethany, Mallard, Mel, Mcconnellogue, Carol-Ann mary, Moroz, George, Murali, Mridhula, Nalborczyk, Ladislas, Nenadić, Filip, Nieder, Jessica, Nikolić, Dušan, Nogueira, Francisco g. s., Offerman, Heather m., Passoni, Elisa, Pélissier, Maud, Perry, Scott j., Pfiffner, Alexandra m., Proctor, Michael, Rhodes, Ryan, Rodríguez, Nicole, Roepke, Elizabeth, Röer, Jan p., Sbacco, Lucia, Scarborough, Rebecca, Schaeffler, Felix, Schleef, Erik, Schmitz, Dominic, Shiryaev, Alexander, Sóskuthy, Márton, Spaniol, Malin, Stanley, Joseph a., Strickler, Alyssa, Tavano, Alessandro, Tomaschek, Fabian, Tucker, Benjamin v., Turnbull, Rory, Ugwuanyi, Kingsley o., Urrestarazu-Porta, Iñigo, Van de vijver, Ruben, Van engen, Kristin j., Van miltenburg, Emiel, Wang, Bruce xiao, Warner, Natasha, Wehrle, Simon, Westerbeek, Hans, Wiener, Seth, Winters, Stephen, Wong, Sidney g.-J., Wood, Anna, Wottawa, Jane, Xu, Chenzi, Zárate-Sández, Germán, Zellou, Georgia, Zhang, Cong, Zhu, Jian, and Roettger, Timo b.

Abstract

Recent empirical studies have highlighted the large degree of analytic flexibility in data analysis that can lead to substantially different conclusions based on the same data set. Thus, researchers have expressed their concerns that these researcher degrees of freedom might facilitate bias and can lead to claims that do not stand the test of time. Even greater flexibility is to be expected in fields in which the primary data lend themselves to a variety of possible operationalizations. The multidimensional, temporally extended nature of speech constitutes an ideal testing ground for assessing the variability in analytic approaches, which derives not only from aspects of statistical modeling but also from decisions regarding the quantification of the measured behavior. In this study, we gave the same speech-production data set to 46 teams of researchers and asked them to answer the same research question, resulting in substantial variability in reported effect sizes and their interpretation. Using Bayesian meta-analytic tools, we further found little to no evidence that the observed variability can be explained by analysts’ prior beliefs, expertise, or the perceived quality of their analyses. In light of this idiosyncratic variability, we recommend that researchers more transparently share details of their analysis, strengthen the link between theoretical construct and quantitative system, and calibrate their (un)certainty in their conclusions.

Published
2023

19. How Voice Analysis Can Help Solve Crimes

Author

Gully, Amelia, Harrison, Philip, Hughes, Vincent, Rhodes, Richard, and Wormald, Jessica

Subjects
General Medicine
Abstract

Imagine you are a police officer investigating a crime in which somebody has made a threatening phone call. There may not be any physical evidence like DNA or fingerprints, but the person’s voice is captured on a recording. Experts can analyze the voice recording and compare it with the voice of a known suspect to find out how likely it is that they are the same person. This method is called forensic voice comparison. It works because people’s voices contain lots of information about them. Your voice tells a story about where you grew up and learned to speak, and your voice also depends on your individual biological make-up. In this article, we explain how this information is used to compare recordings of voices in criminal cases.

Published
2022

25. The use of the vocal profile analysis for speaker characterization : methodological proposals

Author

San Segundo Fernandez, Eugenia, Foulkes, Paul, French, John Peter, Harrison, Philip Thomas, Hughes, Vincent, and Kavanagh, Colleen

Abstract

Among phoneticians, the Vocal Profile Analysis (VPA) is one of the most widely used methods for the componential assessment of voice quality. Whether the ultimate goal of the VPA evaluation is the comparative description of languages or the characterization of an individual speaker, the VPA protocol shows great potential for different research areas of speech communication. However, its use is not without practical difficulties. Despite these, methodological studies aimed at explaining where, when and why issues arise during the perceptual assessment process are rare. In this paper we describe the methodological stages through which three analysts evaluated the voices of 99 Standard Southern British English male speakers, rated their voices using the VPA scheme, discussed inter-rater disagreements, and eventually produced an agreed version of VPA scores. These scores were then used to assess correlations between settings. We show that it is possible to reach a good degree of inter-rater agreement, provided that several calibration and training sessions are conducted. We further conclude that the perceptual assessment of voice quality using the VPA scheme is an essential tool in fields such as forensic phonetics but, foremost, that it can be adapted and modified to a range of research areas, and not necessarily limited to the evaluation of pathological voices in clinical settings.

Published
2019

30. The use of the Vocal Profile Analysis for speaker characterization: Methodological proposals

Author

San Segundo Fernández, Eugenia [0000-0002-0127-552X], San Segundo Fernández, Eugenia, Foulkes, Paul, French, Peter, Harrison, Philip, Hughes, Vincent, Kavanagh, Colleen, San Segundo Fernández, Eugenia [0000-0002-0127-552X], San Segundo Fernández, Eugenia, Foulkes, Paul, French, Peter, Harrison, Philip, Hughes, Vincent, and Kavanagh, Colleen

Abstract

Among phoneticians, the Vocal Profile Analysis (VPA) is one of the most widely used methods for the componential assessment of voice quality. Whether the ultimate goal of the VPA evaluation is the comparative description of languages or the characterization of an individual speaker, the VPA protocol shows great potential for different research areas of speech communication. However, its use is not without practical difficulties. Despite these, methodological studies aimed at explaining where, when and why issues arise during the perceptual assessment process are rare. In this paper we describe the methodological stages through which three analysts evaluated the voices of 99 Standard Southern British English male speakers, rated their voices using the VPA scheme, discussed inter-rater disagreements, and eventually produced an agreed version of VPA scores. These scores were then used to assess correlations between settings. We show that it is possible to reach a good degree of inter-rater agreement, provided that several calibration and training sessions are conducted. We further conclude that the perceptual assessment of voice quality using the VPA scheme is an essential tool in fields such as forensic phonetics but, foremost, that it can be adapted and modified to a range of research areas, and not necessarily limited to the evaluation of pathological voices in clinical settings.

Published
2019

34. Using conjugated diene butyl for radiation-cured PSAs

Author

Merrill, Natalie A., Gardner, Irwin J., and Hughes, Vincent L.

Subjects
Adhesives -- Composition, Butyl rubber -- Usage, Adhesives and sealants industry -- Product development, Business, Chemicals, plastics and rubber industries
Abstract

For many years polyisobutylene and butyl rubber, a modified polyisobutylene containing up to 2 mole % isoprene, have been reported to be polymers that respond to high energy electron beam [...]

Published
1992

43. Front-end approaches to the issue of correlations in forensic speaker comparison

Author

Gold, Erica, Hughes, Vincent, Wolters, Maria, Livingstone, Judy, Beattie, Bernie, Smith, Rachel, MacMahon, Mike, Stuart-Smith, Jane, and Scobbie, Jim

Subjects
H1, HA, PE, QA, P1
Abstract

In likelihood ratio (LR)-based forensic speaker\ud comparison it is essential to consider correlations between parameters to accurately estimate the overall strength of the evidence. Current approaches attempt to deal with correlations after the computation of LRs (back-end processing). This paper explores alternative, front-end techniques, which consider the underlying correlation structure of the raw data. Calibrated LRs were computed for a range of parameters commonly analysed in speaker comparisons. LRs were combined using (1) an\ud assumption of independence, (2) the mean, (3)\ud assumptions from phonetic theory, and (4) empirical correlations in the raw data. System (1), based on an assumption of independence, produced the best validity (Cllr = 0.04). Predictably, overall strength of evidence was also highest for system (1), while strength of evidence was weakest using the mean (2). Both systems (3) and (4) performed well achieving Cllr values of ca. 0.09.

Published
2015

44. Assessing the effects of accent-mismatched reference population databases on the performance of an automatic speaker recognition system

Author

Watt, Dominic, Harrison, Philip, Hughes, Vincent, French, Peter, Llamas, Carmen, Braun, Almut, and Robertson, Duncan

Abstract

Automatic Speaker Recognition (ASR) systems are designed to provide the user with statistics relating to the similarity of two or more speech samples and to the typicality of those shared features in the wider population. When an ASR system is used as part of a forensic investigation, the user must decide what counts as the appropriate ‘wider population’ and select a reference database accordingly. While it has generally been held that the voices populating the reference database should be similar in accent to that of the samples under consideration, the degree to which the accents should correspond has until now not been investigated empirically. We report in this article on a study in which the composition of the reference database was systematically varied in terms of accent, using corpora of samples of Standard Southern British English and of three subvarieties spoken in North-East England (Newcastle, Sunderland, Middlesbrough).

Published
2020
Full Text
View/download PDF

46. Toward cyber-centric management of policing: back to the future with information and communication technology

Author

Hughes, Vincent and Love, Peter E.D.

Subjects
Law enforcement -- Technology application, Law enforcement -- Methods, Law enforcement -- Comparative analysis, Computers -- Services, Computers -- Usage, Technology application, Business, Business, general, Computers and office automation industries
Abstract

The article presents a framework to develop and implement virtual policing with information and communication technology, using Western Australia as an example. Topics include new public management practices favored by government versus traditional services expected by the public.

Published
2004

47. The effect of speaker sampling in likelihood ratio based forensic voice comparison

Author

Xiao Wang, Bruce, Hughes, Vincent, and Foulkes, Paul

Abstract

Within the field of forensic voice comparison (FVC), there is growing pressure for experts to demonstrate the validity and reliability of the conclusions they reach in casework. One benefit of a fully data-driven approach that utilises databases of speakers to compute numerical likelihood ratios (LRs) is that it is possible to estimate validity and reliability empirically. However, little is known about the stability of LR output as a function of the specific speakers sampled for use in the training, test and reference data sets. The present study addresses this issue using two large sets of formant data: Cantonese sentence final particle /a/ and British English filled pauses UM. Experiments were replicated 100 times varying the 1) training, test and reference speakers, 2) training speakers only, 3) test speakers only, and 4) reference speakers only. The results show that varying the speakers in all three sets has the greatest effect on system stability for both the Cantonese and English variables, with the Cllr varying from 0.60 to 0.97 for /a/ and 0.32 to 1.33 for UM. However, this variability is primarily due to the effects of uncertainty in the test set. Varying only the training speakers has the least effect on system stability for /a/ (Cllr range: 0.76 to 0.88), while varying reference speakers has the smallest effect for UM (Cllr range: 0.40 to 0.54). The results indicate that in LR-based FVC it is important to assess the stability of the system as a function of the samples of speakers used (Cllr range) rather than just reporting a single Cllr value based on one configuration of speakers in each set. The study contributes to the general debate on reporting uncertainty in LR computation.

Published
2019
Full Text
View/download PDF

48. The effect of variability on the outcome of likelihood ratios

Author

Hughes, Vincent

Abstract

The likelihood ratio (LR) is the “logically and legally correct” (Rose and Morrison 2009:143) framework for the estimation of strength-of-evidence under two competing hypotheses. In forensic voice comparison these considerations are reduced to the similarity and typicality of features across a pair of suspect and offender samples. However, typicality can only be judged against patterns in the relevant population (Aitken and Taroni 2004:206). In calculating numerical LRs typicality is assessed relative to a sub-section of that population. This study considers issues of variability relating to the delimitation of reference data with regard to the number of speakers and number of tokens per speaker. Using polynomial estimations of F1 and F2 trajectories from spontaneous GOOSE (Wells 1982), LR comparisons were performed against a reference set of up to 120 speakers and up to 13 tokens per speaker. Results suggest that mean same-speaker LRs are robust to such variation until the reference data is limited to small numbers of speakers and tokens. However, variance and severity of error may be continually reduced with the inclusion of more data. The definition of the relevant population with regard to regional variety is also assessed. Results for LRs are presented across four sets of test data where only one set matches the reference population for accent. In the absence of differences in levels of within-speaker variation, the magnitude of same-speaker LRs and severity of error are shown to be considerably higher for the ‘mismatch’ test sets. However, results indicate that the removal of regionally-defining acoustic information may reduce the effect of accent divergence between the evidential and reference data. This has positive implications for the application of the numerical LR approach.

Published
2011

Catalog

Books, media, physical & digital resources
See catalog results