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X-WR-CALNAME:Department of Linguistics, HKU
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X-WR-CALDESC:Events for Department of Linguistics, HKU
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TZID:Asia/Shanghai
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DTSTART:20170101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Shanghai:20180918T153000
DTEND;TZID=Asia/Shanghai:20180918T170000
DTSTAMP:20180911T162809Z
CREATED:20180907T141806Z
LAST-MODIFIED:20180911T162809Z
UID:3839-1537284600-1537290000@linguistics.hku.hk
SUMMARY:Strength of Forensic Voice Comparison Evidence from Long-term Fundamental Frequency in Chinese Conversations - Phil Rose (Australian National University)
DESCRIPTION:In forensic speaker identification\, the expert typically compares questioned and known voice samples to help determine whether the questioned voice has come from the known speaker. Usually the questioned sample is from an offender and the known sample from a suspect\, and the beneficiary is a fact-finder\, e.g. judge or jury\, or an investigating authority\, e.g. police. \n  \nOne popular acoustic-phonetic feature in forensic semi-automatic speaker recognition – its mean and standard deviation values reportedly used by 94% and 72% of forensic voice comparison experts world-wide – is fundamental frequency (F0)\, the acoustic reflex of the rate of vibration of the vocal cords. This is because of promising results in early speaker recognition research\, and also because F0 is relatively easily measurable and there is usually lots of it. F0 is also relatively immune to channel distortion. \n  \nThe most important property of any feature used to help identify voices forensically is its demonstrable effectiveness in discriminating same-speaker speech samples from different-speaker speech samples\, and it must have been shown to do so under the conditions of the forensic case in which the feature is being used: \n  \n\nWithout actual empirical evidence of the ability of a forensic feature-comparison method to produce conclusions at a level of accuracy appropriate to its intended use under circumstances reasonably related to this use\, an examiner’s conclusion that two samples are likely to have come from the same source is completely meaningless.”  [E.S. Lander: ‘Response to the ANZFSS council statement on the President’s Council of Advisors on Science and Technology Report.’ Australian J. Forensic Sci. 2017]\n\n  \nAs well as the many linguistic uses of F0\, which encodes tone\, intonation and stress\, many non-linguistic factors\, like state of health\, are also known to affect it. This multiplicity of factors has an adverse effect on its between- to within-speaker variance ratio by increasing the latter. Since the inherent strength of forensic speaker recognition features relies primarily on their ratio of within- to between-speaker variance\, one would not expect particularly good strength of evidence from global F0 properties\, and this has been demonstrated in several studies. These studies have\, however\, also used arguably ecologically less than valid material\, or at least material less likely to occur in real cases\, for example\, contemporaneous recordings or monologs of varying\, but atypically long\, duration. Such conditions also have the potential to overestimate the strength of evidence of uncontrolled global F0.  \n  \nOne relationship between suspect and offender recordings which is commonly found in real-world case-work\, but which does not seem to have been tested\, is mismatch in formality between the conditions under which the suspect and offender voice recordings are obtained. Typically\, the suspect’s recordings are taken from a formal police interview\, whereas the offender’s recordings are from informal conversational exchanges. The aim of the research described in this talk was to test how well F0 from natural speech performs\, in particular under these mismatched conditions. We used a database of non-contemporaneous recordings of informal conversations\, simulated police interrogations\, and information exchanges from 90 male Chinese speakers of North-Eastern Mandarin. The database was recorded in 2011 for the purpose of aiding forensic voice comparison research and practice. The data were evaluated within the likelihood ratio framework\, which was recently endorsed as best practice in forensic automatic and semi-automatic speaker recognition by the Board of the European Network of Forensic Science Institutes\, representing 58 laboratories in 33 countries. In the talk I will also explain the likelihood ratio approach and how it is used to estimate the strength\, and weight\, of evidence.
URL:https://linguistics.hku.hk/event/strength-of-forensic-voice-comparison-evidence-from-long-term-fundamental-frequency-in-chinese-conversations-phil-rose-australian-national-university/
LOCATION:Room 4.04\, Run Run Shaw Tower\, Centennial Campus\, HKU\, Hong Kong
CATEGORIES:Seminars
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DTSTART;TZID=Asia/Shanghai:20180920T153000
DTEND;TZID=Asia/Shanghai:20180920T170000
DTSTAMP:20180911T162912Z
CREATED:20180907T141544Z
LAST-MODIFIED:20180911T162912Z
UID:3835-1537457400-1537462800@linguistics.hku.hk
SUMMARY:Concrete analysis of abstract segments: Absolute neutralization in an Emergent grammar - Diana Archangeli (University of Arizona)
DESCRIPTION:A challenge facing phonological theories is that many analyses result in fairly abstract solutions. The typical situation arises when “the same” element behaves differently\, depending on the context. There are numerous examples; a few are given here. \n\nIn Barrow Inupiaq\, the vowel [i] either triggers palatalization or assimilates to other vowels but never both: this has been treated as two distinct underlying representations converging on a single surface form (Kaplan 1981\, Archangeli & Pulleyblank 1994)\nIn Polish\, non-alternating C[e]C-final forms and non-alternating CC-final forms both contrast with the alternating C[e]C~CC final forms\, leading to the hypothesis of yers\, “vowels” at the ends of certain morphemes – and some of these yers simply never surface. (Jarosz 2005\, Archangeli & Pulleyblank in prep)\nIn Malagasy\, [v] alternates with [mb] in some morphemes while in others\, [v] alternates with [m] (Garvey 1964\, Archangeli & Pulleyblank in prep)\n\nIn this talk\, I explore the Emergent grammar approach to absolute neutralization\, arguing that the “phenomenon” is theory-internal. With different assumptions\, there is no need for abstract segments\, and the apparent neutralisation is simply one manifestation of the continuum of variation found in language.
URL:https://linguistics.hku.hk/event/concrete-analysis-of-abstract-segments-absolute-neutralization-in-an-emergent-grammar-diana-archangeli-university-of-arizona/
LOCATION:Room 4.04\, Run Run Shaw Tower\, Centennial Campus\, HKU\, Hong Kong
CATEGORIES:Seminars
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