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Speech Recognition

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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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Contents:

• Continuous/Discrete

• How does it work?

• Recent improvements

• Current software options

• Future of SR

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Continuous or Discrete?

• Continuous speech

- dictation

• Discrete speech

- system controls

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How does SR work?

• Recognition

• Training

• Correction

• Command/Control

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Recognition (1)

Voice Input Analog to Digital Acoustic Model

Language Model

Display Speech EngineFeedback

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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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Recognition (3)

Language Modeling

• Word context

• Word frequency

• Transition possibilities

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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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Voice Training (2)

User specific Voice file

• Voice qualities

• Pronunciation

• Patterns of word use

• Preferred vocabulary

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Making Corrections

• Move cursor by voice command

• Memorize edit commands

• List of possible alternatives

• Make correction manually

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Command/Control

• Desktop grid

• Program or Link name/number

• URL name

• Memorized commands

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Recent Improvements in SR

• Faster training ~10 min.

• Better recognition ~95%

• More compatible software

• Better system control/command

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Current Software Options for PC

• Dragon Systems – Naturally Speaking

• Philips – FreeSpeech

• IBM – ViaVoice

• Lernout & Hauspie – Voice Xpress

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How well do the work?

Training Dictation Correct.

App.

Integrat.

Command

- 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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Future of SR

• SUI – Speech-based User Interface

• Improvements needed:

- Greater accuracy

- Greater system control/command

- More compatible software

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Conclusion

• SR Uses

• How does it work?

• Current Software

• Problems of SR

• More SR coming soon….

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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.