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Building Fault Tolerant Voice User Interfaces. SpeechTEK 2007. Tuesday, August 21 Track B “Getting the VUI Right when Recognition Goes Wrong”. Versay Solutions, LLC. Daniel Padgett Senior Speech Technology Consultant Jessica Peterson Hicks, Ph.D. Speech Technology Consultant.
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Building Fault Tolerant Voice User Interfaces SpeechTEK 2007 Tuesday, August 21 Track B “Getting the VUI Right when Recognition Goes Wrong”
Versay Solutions, LLC Daniel Padgett Senior Speech Technology Consultant Jessica Peterson Hicks, Ph.D. Speech Technology Consultant
Fault Tolerant Voice User Interfaces • Error Prevention • Error Resolution
Directed Dialog • Prompt Design • Grammar Coverage
Proof of Concept NL Routing Application • Natural Language (NL) Main Menu • “How can I help you?” • Main Menu Confirmation • “Back Off” Menu to support Main Menu failures • Disambiguation dialog states • Form-filling dialog states
Case Study – Back Off Main Menu • Initial Prompt • Designed to handle exception cases from Main Menu • Options mapped to core business practices • Grammar • Optimally constrained static grammar • 5 slots / semantic interpretations
Case Study – Main Menu Confirmation • Initial Prompt • Dynamically constructed • Covered ~100 categories “Okay. [You need to change your address.] Is that right?” • Grammar • Optimally constrained static grammar • 2 slots / semantic interpretations
Robust Interpretation (RI) • Statistical Language Models • Interpretation Grammars
RI – Back Off Main Menu • Statistical Language Model • Training set of ~2500 utterances • Test set of ~1000 utterances • Interpretation Grammar • 8 slots / semantic interpretations
RI – Main Menu Confirmation • Statistical Language Model • Training set of ~3000 utterances • Test set of ~1000 utterances • Interpretation Grammar • 20 slots / semantic interpretations • Y, N, N+RoutingCategory, RoutingCategory
Error Prevention - Summary • Robust Interpretation for two key states • Considerable increases in coverage • Significant decreases in no-match rates • Minimal False-Accepts
Fault Tolerant Voice User Interfaces • Error Prevention • Error Resolution
Error Resolution • Dialog State Error Strategy • Universal Error Strategy • Task-related Error Strategy
Established Methods • Dialog State Error Handling • Escalating error strategy • No-input and no-match handlers • Implicit DTMF • Universal Error Handling • Increment for each no-match, no-input • Transfer when maximum exceeded
Dialog State Error Strategy • Escalating error handling • Rapid reprompt • Explicit DTMF on penultimate error prompt • Transfer on final error • Combination of no-match and no-input handlers
Universal Error Strategy • Increment / decrement counter • Score errors on distinct dimensions • Number • Consecutivity
Task-related Error Strategy • Determine “sensitivity” level for each call path • Allow fewer errors on sensitive paths, more errors on less sensitive paths • Report a Problem = highly sensitive • Monthly Payment = moderately sensitive • Hours of Operation / Location = less sensitive
Customer Service Universals • Acknowledge • Explain • Re-prompt
Summary Fault Tolerance means striking the right balance between: • Error Prevention • Error Resolution
Contact Us www.versay.com dpadgett@versay.com jhicks@versay.com (888) 869-0121