Speech recognition technology allows users to control systems and enter text using their voice. It works by converting voice input to digital signals, analyzing the sounds using acoustic and language models, and outputting text. Current software provides over 95% accuracy for dictation with training and has improved at system commands. Further advances are still needed to achieve greater accuracy and compatibility across different applications.

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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