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Improved Name Recognition with Meta-data Dependent Name Networks published by Sameer R. Maskey, Michiel Bacchiani, Brian Roark, and Richard Sproat presented by Irina Likhtina. Problem: General Name Transcription Improvement. Solutions that use no prior knowledge require large increase in
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Improved Name Recognitionwith Meta-data Dependent Name Networkspublished by Sameer R. Maskey, Michiel Bacchiani,Brian Roark, and Richard Sproatpresented by Irina Likhtina
Problem: General Name Transcription Improvement Solutions that use no prior knowledge require large increase in • Size • Complexity • Ambiguity because any improvement accomplished before was possible only through an increase in lexicon used.
Paper’s Solution • Use meta-data at runtime in the form of • Caller ID string – “cname” • Name of mailbox owner – “mname” This meta-data is reasonably available due to the prevalence of caller identification given by phone companies.
Database Used • Scanmail training corpus of 100 hours of voicemail messages from 140 employees of AT&T. • Manually transcribed with “cname” and “mname” tags • Gender balanced • ~12% non-native speakers • 238 random messages for testing, everything else (~ 10,000 messages) for training
Approach • Three steps of the algorithm: • create a class-based language model • create a name network that will give instances for the classes of the model • replace the class-based language model at runtime with the name networks
Class-Based Language Model • Manual tags of mailbox name and caller name for each message replaced with “mname” and “cname” labels • “mname” and “cname” represented the 2 class tokens that can be substituted with any values in the future
Name Network • To get the values for “mname” and “cname”, an internal AT&T employee directory (~ 40,000 people) listing was used • “cname” created from variations of static titles (Miss, Mr), full first names and nicknames (Alexander, Alex), and last names (Jones)
Name Network (continued) • Probability within class – training corpus • Probability within first names – AT&T directory listing
Replacement in the ASR network • State of art before proposed algorithm: off-line composition, determinization and optimization of one existing grammar G and one lexicon L Proposed algorithm is impracticalwith off-line composition because of so many variations needed • Proposed algorithm: L by G optimization done for each class using G specific for that class Small overhead of proposed algorithm compared to off-line optimization
Experimental results • Word Error Rates (WER) improvement small • Absolute reduction of 0.6% • Named Error Rate (NER) improvement significant • Absolute reduction of 20 %
Conclusions • Large reduction in NER is very critical: • Name transcription is the goal • Scanmail users expressed a strong desire for the system to recognize names correctly • Other improvements: • Errors in OOV • In-vocabulary name recognition • No significant increase in complexity with good name coverage • No need for manual design when the system is moved to new environment