Method and system using separate context and constituent probabilities for speech recognition in languages with compound words
First Claim
1. A method for speech recognition in languages with compound words, comprising the following steps:
- storing phonetic transcriptions of words and components of compound words in a first storage area,calculating n-gram frequencies (language model) for the probability of a compound word within a sequence of N words with use of a previously processed body of text, and storing the frequencies in a second storage area;
recording and digitizing the acoustic speech signal and storing the digitized speech signal in a third storage area, wherein by means of signal processing based on the phonetic transcriptions, approximately determining the words and boundaries of compound words and deriving hypothetical sequences of words or candidates for compound words therefrom;
establishing separate processing paths for sequences of candidates for words and compound words;
statistically evaluating the processing paths by means of the n-gram frequencies, where likelihood profiles are generated from the sequence of n-gram frequencies of words or components of compound words of each processing path; and
fully evaluating the processing paths with regard to the goodness of acoustic fit and the statistical probability of the language model.
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Abstract
In a method and system for speech recognition in the case of languages containing compound words only components of compound words are stored in a language model. Only these components are handled in the vocabulary.
In recognizing possible compound words separate processing paths are set up for the corresponding components of compound words and for possible individual words, in which specific language model statistics are calculated. The basis for the language model statistics is the breakdown of the probabilities, in which the context and the constituents of a compound word are taken into account separately. For this, use is made of the fact, known from linguistics, that grammar-determining components of a compound word are, as a rule, to be found at the end of the compound word, where this constituent of the compound word provides information on gender, case and number of the compound word.
The invention is particularly suitable for real-time speech recognition in discrete and continuous dictation.
36 Citations
16 Claims
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1. A method for speech recognition in languages with compound words, comprising the following steps:
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storing phonetic transcriptions of words and components of compound words in a first storage area, calculating n-gram frequencies (language model) for the probability of a compound word within a sequence of N words with use of a previously processed body of text, and storing the frequencies in a second storage area; recording and digitizing the acoustic speech signal and storing the digitized speech signal in a third storage area, wherein by means of signal processing based on the phonetic transcriptions, approximately determining the words and boundaries of compound words and deriving hypothetical sequences of words or candidates for compound words therefrom; establishing separate processing paths for sequences of candidates for words and compound words; statistically evaluating the processing paths by means of the n-gram frequencies, where likelihood profiles are generated from the sequence of n-gram frequencies of words or components of compound words of each processing path; and fully evaluating the processing paths with regard to the goodness of acoustic fit and the statistical probability of the language model. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for speech recognition in languages containing compound words comprising:
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recording means for recording acoustic speech signals; A/D converter means for digitizing the analog acoustic speech signal; phonetic transcription means for constructing a number of phonetic transcriptions of words and components of compound words; listing means for constructing lists relating to single words, beginnings of compound words and endings of compound words; probability means for determining the speech pattern probabilities for each on a processing path for the lists; profiling means for determining likelihood profiles for hypothetical word or compound word sequences; and processing path means for producing and cancelling processing paths and for deciding on the production and cancellation of processing paths. - View Dependent Claims (13, 14, 15, 16)
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Specification