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LREC 2008 1 Combining Multiple Models for Speech Information Retrieval Muath Alzghool and Diana Inkpen University of Ottawa Canada
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LREC 2008 2 Presentation Outline Task: Speech Information Retrieval. Data: Mallach collection (Oard et al, 2004). System description. Model fusion. Experiments using model fusion. Results of the cross-language experiments. Results of manual keywords and summaries. Conclusion and future work.
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LREC 2008 3 The Mallach collection Used in the Cross-Language Speech Retrieval (CLSR) task at Cross-Language Evaluation Forum (CLEF) 2007. 8104 “documents” (segments) from 272 interviews with Holocaust survivors, totaling 589 hours of speech: ASR transcripts with a word error rate of 25-38%. Additional metadata: automatically-assigned keywords, manually-assigned keywords, and a manual 3-sentence summary. A set of 63 training topics and 33 test topics, created in English from actual user requests and translated into Czech, German, French, and Spanish by native speakers. Relevance judgments were generated standard pooling.
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LREC 2008 4 Segments VHF[IntCode]-[SegId].[SequenceNum] Interviewee name(s) and birthdate Full name of every person mentioned Thesaurus keywords assigned to the segment 3-sentence segment summary ASR transcript produced in 2004 ASR transcript produced in 2006 Thesaurus keywords from a kNN classifier Thesaurus keywords from a second kNN classifier
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LREC 2008 5 Example topic (English) 1159 Child survivors in Sweden Describe survival mechanisms of children born in 1930- 1933 who spend the war in concentration camps or in hiding and who presently live in Sweden. The relevant material should describe the circumstances and inner resources of the surviving children. The relevant material also describes how the wartime experience affected their post-war adult life.
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LREC 2008 6 Example topic (French) 1159 Les enfants survivants en Suède Descriptions des mécanismes de survie des enfants nés entre 1930 et 1933 qui ont passé la guerre en camps de concentration ou cachés et qui vivent actuellement en Suède. Les documents recherches devront décrire les circonstances ainsi que les ressources propres aux enfants ayant survécu. Les documents en question devront décrire également l'influence que l'expérience de la guerre a eu sur leur vie d'adulte après la guerre.
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LREC 2008 7 System Description SMART: Vector Space Model (VSM). Terrier: Divergence from Randomness models (DFR). Two Query Expansion Methods: Based on thesaurus (novel technique). Blind relevance feedback (12 terms from the top 15 documents): based on Bose-Einstein 1 model (Bo1 from Terrier). Model Fusion: sum of normalized weighted similarity scores (novel way to compute weights). Combined output of 7 machine translation tools.
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LREC 2008 8 Model Fusion Combine the results of different retrieval strategies from SMART (14 runs) and Terrier (1 run). Each technique will retrieve different sets of relevant documents; therefore combining the results could produce a better result than any of the individual techniques.
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LREC 2008 9 Experiments using Model Fusion Applied the data fusion methods to 14 runs produced by SMART and one run produced by Terrier. % change is given with respect to the run providing better performance in each combination on the training data. Model fusion helps to improve the performance (MAP and Recall score) on the test data. Monolingual (English): 6.5% improvement (not statistically significant). Cross-language experiments (French) : 21.7% improvement (significant).
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LREC 2008 10 Experiments using Model Fusion (MAP) Weighting scheme Manual En Auto-English Auto- FrenchAuto- Spanish Train.TestTrain.TestTrain.TestTrain.Test 1.nnc.ntc0.25460.22930.0888 0.0819 0.07920.0550.05930.0614... 11.nnn.ntn0.24760.2228 0.09000.0852 0.07990.05030.05990.061 12.ntn.nnn0.27380.2369 0.09330.0795 0.08430.05070.06910.0578 13.ltn.ntn0.28580.245 0.09690.0799 0.09050.05660.07010.0589 14.atn.ntn0.28430.2364 0.06200.0546 0.07220.03470.05860.0355 15.In(exp)C2 0.3177 0.2737 0.08850.0744 0.09080.04870.07470.0614 Fusion 1 0.32080.27610.09690.0855 0.09120.06220.07310.0682 % change1.0%0.9%0.0%6.5%0.4%21.7%-2.2%10.0% Fusion 2 0.31820.27410.09750.0842 0.09420.06020.07520.0619 % change0.2%0.1%0.6%5.1%3.6%19.1%0.7%0.8%
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LREC 2008 11 Experiments using Model Fusion (Recall) Weighting scheme Manual En Auto-English Auto- FrenchAuto- Spanish Train.TestTrain.TestTrain.TestTrain.Test 1.nnc.ntc23711827 17261306 1687112215621178... 11.nnn.ntn23701823 17401321 1748115816431190 12.ntn.nnn23701823 17401321 1748115816431190 13.ltn.ntn24331876 15821215 1478107014081134 14.atn.ntn24421859 14551101 139097512971037 15.In(exp)C2 2638 1823 16241286 1676106116311172 Fusion 126451832 17451334 1759114716451219 % change0.3%0.5 %0.3%1.0%0.6%-1.0%0.1%2.4% Fusion 226471823 17271337 1736109816311172 % change 0.3%0.0% 0.8%1.2%-0.7% -5.5%-0.7%-1.5%
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LREC 2008 12 Results of the cross-language experiments The cross-language results for French are very close to Monolingual (English) on training data (the difference is not significant), but not on test data (the difference is significant). The difference is significant between cross-language results for Spanish and Monolingual (English) on training data but not on test data (the difference is not significant). LanguageTrainingTest 1 English0.09690.0855 2 French0.09120.0622 3 Spanish0.07310.0682
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LREC 2008 13 Results of manual keywords and summaries LanguageTrainingTest 1 Manual English 0.320810.2761 2 Auto-English 0.09690.0855 Experiments on manual keywords and manual summaries showed high improvements comparing to Auto-English. Our results (for manual and automatic runs) are the highest to date on this data collection in CLEF/CLSR.
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LREC 2008 14 Conclusion and future work Model fusion helps to improve the retrieval significantly for some experiments (Auto-French) and for other not significantly (Auto-English). The idea of using multiple translations proved to be good (based on previous experiments). Future work we plan to investigate more methods of model fusion. Removing or correcting some of the speech recognition errors in the ASR content words.
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