1. Speech Recognition
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2. Introduction
• What is Speech Recognition?
- Voice Recognition?
• Where can it be used?
- Dictation
- System control/navigation
- Commercial/Industrial applications
- Hand held digital recorders
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3. Contents:
• Continuous/Discrete
• How does it work?
• Recent improvements
• Current software options
• Future of SR
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4. Continuous or Discrete?
• Continuous speech
- dictation
• Discrete speech
- system controls
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5. How does SR work?
• Recognition
• Training
• Correction
• Command/Control
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6. Recognition (1)
Voice Input Analog to Digital Acoustic Model
Language Model
Feedback Display Speech Engine
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7. Recognition (2)
Acoustic Modeling
• Spoken words: “I think there are…..”
• Phonemes: ‘ ay th-in-nk-kd dh-eh-r aa-
r’
• H.M.M.’s: 5 state representation
• Speech Engine
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8. Recognition (3)
Language Modeling
• Word context
• Word frequency
• Transition possibilities
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9. Voice Training (1)
Can be done by:
• Predetermined text segments
• Individual words
Compare new acoustic with old and combines
• More training = better recognition
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10. Voice Training (2)
User specific Voice file
• Voice qualities
• Pronunciation
• Patterns of word use
• Preferred vocabulary
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11. Making Corrections
• Move cursor by voice command
• Memorize edit commands
• List of possible alternatives
• Make correction manually
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12. Command/Control
• Desktop grid
• Program or Link name/number
• URL name
• Memorized commands
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13. Recent Improvements in SR
• Faster training ~10 min.
• Better recognition ~95%
• More compatible software
• Better system control/command
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14. Current Software Options for PC
• Dragon Systems – Naturally Speaking
• Philips – FreeSpeech
• IBM – ViaVoice
• Lernout & Hauspie – Voice Xpress
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15. How well do the work?
Training Dictation App. Command
Correct. Integrat. - Control
Dragon Excellent Excellent Good Good
Philips Fair Fair Good Good
IBM Excellent Good Good Excellent
L&H Good Good Good Good
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16. Future of SR
• SUI – Speech-based User Interface
• Improvements needed:
- Greater accuracy
- Greater system control/command
- More compatible software
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17. Conclusion
• SR Uses
• How does it work?
• Current Software
• Problems of SR
• More SR coming soon….
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18. References
• 1. Alwang, Greg. “Speech Recognition,” PC Magazine, December 1
1999
• 2. Hauptmann, Alexander G. Jang, Photina Jaeyun. Carnegie Mellon
University. “Learning to Recognize Speech by Watching Television,”
IEEE Intelligent Systems, September/October 1999.
• 3. Miastkowski, Stan. “Latest Speech Software Gets You Up and
Running Faster,” PC World, November 1999.
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