Java Speech API
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• Text pre-processing: Analyzes the input text for special constructs of the language. In English, special treatment is required for abbreviations, acronyms, dates, times, numbers, currency amounts, e-mail addresses, and many other forms. Other languages need special processing for these forms, and most languages have other specialized requirements.
The result of these first two steps is a spoken form of the written text. Here are examples of the differences between written and spoken text:
St. Matthew's hospital is on Main St.
-> “Saint Matthew's hospital is on Main Street”
Add $20 to account 55374.
-> “Add twenty dollars to account five five, three seven four.”
The remaining steps convert the spoken text to speech:
• Text-to-phoneme conversion: Converts each word to phonemes. A phoneme is a basic unit of sound in a language.
• Prosody analysis: Processes the sentence structure, words, and phonemes to determine the appropriate prosody for the sentence.
• Waveform production: Uses the phonemes and prosody information to produce the audio waveform for each sentence.
Speech synthesizers can make errors in any of the processing steps described above. Human ears are well-tuned to detecting these errors, but careful work by developers can minimize errors and improve the speech output quality.
Speech recognition
Speech recognition provides computers with the ability to listen to spoken language and determine what has been said. In other words, it processes audio input containing speech by converting it to text.
The major steps of a typical speech recognizer are as follows:
• Grammar design: Defines the words that may be spoken by a user and the patterns in which they may be spoken.
• Signal processing: Analyzes the spectrum (i.e., the frequency) characteristics of the incoming audio.
• Phoneme recognition: Compares the spectrum patterns to the patterns of the phonemes of the language being recognized.
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