Dragon Systems, Inc.

Jed M Roberts

Joel M Gould

James K Baker

Frank J McGrath

Joel W Parke

Steven D Squires

Dean G Sturtevant

Peter S Heitman

Elizabeth E Steele

Paul G Bamberg

Claudia L Ellermann

Stijn VanEven

Caroline B Huang

A word recognition system can: respond to the input of a character string from a user by limiting the words it will recognize to words having a related, but not necessarily the same, string; score signals generated after a user has been prompted to generate a given word against words other than the prompted word to determine if the signal should be used to train the prompted word; vary the number of signals a user is prompted to generate to train a given word as a function of how well the training signals score against each other or prior models for the prompted word; create a new acoustic model of a phrase by concatenating prior acoustic models of the words in the phrase; obtain information from another program running on the same computer, such as its commands or the context of text being entered into it, and use that information to vary which words it can recognize; determine which program unit, such as an application program or dialog box, currently has input focus on its computer and create a vocabulary state associated with that program unit into which vocabulary words which will be made active when that program group has the focus can be put; detect the available computational resources and alter the instructions it executes in response; test if its ability to respond to voice input has been shut off without user confirmation, and, if so, turn that ability back on and prompt the user to confirm if that ability is to be turned off, store both a first and a second set of models for individual vocabulary words and enable a user to selectively cause the recognizer to disregard the second set of models for a selected word; and/or score a signal representing a given word against models for that word from different word model sets to select which model should be used for future recognition.

Apparatuses and methods for training and operating speech recognition

A word recognition system can: respond to the input of a character string from a user by limiting the words it will recognize to words having a related, but not necessarily the same, string; score signals generated after a user has been prompted to generate a given word against words other than the prompted word to determine if the signal should be used to train the prompted word; vary the number of signals a user is prompted to generate to train a given word as a function of how well the training signals score against each other or prior models for the prompted word; create a new acoustic model of a phrase by concatenating prior acoustic models of the words in the phrase; obtain information from another program running on the same computer, such as its commands or the context of text being entered into it, and use that information to vary which words it can recognize; determine which program unit, such as an application program or dialog box, currently has input focus on its computer and create a vocabulary state associated with that program unit into which vocabulary words which will be made active when that program group has the focus can be put; detect the available computational resources and alter the instructions it executes in response; test if its ability to respond to voice input has been shut off without user confirmation, and, if so, turn that ability back on and prompt the user to confirm if that ability is to be turned off; store both a first and a second set of models for individual vocabulary words and enable a user to selectively cause the recognizer to disregard the second set of models for a selected word; and/or score a signal representing a given word against models for that word from different word model sets to select which model should be used for future recognition.

Speech recognition system which selects one of a plurality of vocabulary

A computerized word recognition system, such as a speech recognition system, stores word models of a first and second set for each of a plurality of vocabulary words. The system has a user interface which enable a user to selectively prevent the use of a second set's word model for a selected word. Often the first set of word models are spelled word models, such as models represented by a sequence of phonetic component models, each of is derived from similar speech sounds occurring in different words. In such systems the second set of word models are custom words models derived largely from word signals which are presumed to correspond only to the model's associated word. In many embodiments, the user interface allows a user to select to stop using a selected word's custom, or second set, model by selecting a menu or control window of a user interface. It is preferred that the system automatically create custom models when word signals presumed to correspond to a given word score poorly against the word's spelled model. It is also preferred that the system respond to a command to delete a word's custom model by increasing, in subsequent adaptive training of word components for the word's spelled model, the weight given to information from such subsequent word signals relative to model information previously associated with such word components. This is done, in such a case, to compensate for the fact that past training data for the word has probably been corrupted.

Word recognition system which stores two models for some words and

A word recognition system detects the computational resources available to it, such as the speed or number of processors, or whether there is DSP hardware, and alters the instructions it executes in response. The system can be a word recognition program designed to run on different computers having different computational resources. The program receives user generated word signals representing words to be recognized; performs pattern matching on them to select which vocabulary words most probably correspond to such word signals; detects if certain computational resources are available; and varies the instructions it executes in response. In many embodiments the system is a speech recognition program. The word recognition program can vary the computational intensity of its signal processing as a function of available computational resources. Preferably it can match the same word models against representations of word signals produced both by its more and less intensive signal processing. For example, the more intense signal processing might take more frequent FFTs, but average them over the same time period at which the less intense signal processing takes FFTs, so both can represent word signals with the same data structure. If the program detects both a CPU and a DSP processor, it can cause the DSP to determine when the program should interrupt the CPU. The program can also vary the rate at which it filters relatively low scoring words out of consideration during the recognition process as a function of the level of available computational resources.

Word recognition system which alters code executed as a function of

A computerized speech recognition system creates acoustic models of phrases by concatenating acoustic models for individual words. The system stores an acoustic word model and spelling for each of its vocabulary words. When it receives the spelling of a multi-word phrase to be treated as a new vocabulary word, it stores that multi-word spelling as the spelling of the new vocabulary word, and a new acoustic model created by concatenating the acoustic word models of previous vocabulary words whose spellings correspond to words in the multi-word spelling as the acoustic model for the new word. The system can then perform speech recognition by comparing acoustic signals against the word models of stored vocabulary words, including those representing such multi-word phrases. Preferably when a multi-word model is formed, the individual acoustic models concatenated are modified to represent the coarticulation which takes place between words spoken continuously. This can be done by representing word models as sequences of individual phonemes, individual phonemes by phoneme-in-context models, and coarticulation by modifying the phoneme-in-context models of phonemes adjacent the boundary between concatenated words models to reflect the context of the phonemes on the other side of such word boundaries. The system can be a discrete word recognizer. The multi-word phrases can be selected by a user or be obtained from other programs running on the same computer as the speech recognizer, such as from one or more commands available in another program.

Speech recognition system which creates acoustic models by concatenating

Words are added to a speech recognition system vocabulary during user dictation by (a) extracting, from a multi-word user utterance, speech frames that correspond to each one of the one or more new words; and (b) building speech models for the one or more new words using the extracted speech frames.

Building speech models for new words in a multi-word utterance

A system and associated methods for recognizing compound words from an utterance containing a succession of one or more words from a predetermined vocabulary. At least one of the words in the utterance is a compound word including at least two formatives in succession, wherein those formatives are words in the vocabulary.

Speech recognition system for languages with compound words

A method for creating word models for a large vocabulary, natural language dictation system. A user with limited typing skills can create documents with little or no advance training of word models. As the user is dictating, the user speaks a word which may or may not already be in the active vocabulary. The system displays a list of the words in the active vocabulary which best match the spoken word. By keyboard or voice command, the user may choose the correct word from the list or may choose to edit a similar word if the correct word is not on the list. Alternately, the user may type or speak the initial letters of the word. Then the recognition algorithm is called again satisfying the initial letters, and the choices displayed again. A word list is then also displayed from a large backup vocabulary. The best words to display from the backup vocabulary are chosen using a statistical language model and optionally word models derived from a phonemic dictionary. When the correct word is chosen by the user, the speech sample is used to create or update an acoustic model for the word, without further intervention by the user. As the system is used, it also constantly updates its statistical language model. The system gets more and more word models and keeps improving its performance the more it is used. The system may be used for connected speech as well as for discrete utterances.

Method for interactive speech recognition and training

A speech detection system compares the amplitude of an audio signal during successive time periods with speech detection thresholds, and generates an indication of whether the signal contains speech. It derives a background amplitude level from portions of the signal which it indicates do not contain speech, and improves its speech detection by altering the amplitude of the audio signal relative to the speech detection thresholds as a function of this background level. Preferably the background amplitude level is a moving average, which is repeatedly recalculated and repeatedly used to alter the relative amplitude of the audio signal and the detection thresholds. The apparatus uses a measure of the variability of the background amplitude to improve its speech detection. It generates start-of-speech and end-of-speech indications when the amplitude crosses respective thresholds for specified numbers of frames. The background amplitude level is calculated from frames which precede the start-of-speech indication by a predetermined amount and which follow the end-of-speech indication. The invention also provides a speech recognition system which compares the amplitudes an audio signal against the amplitudes of acoustic models of vocabulary words to determine which vocabulary words correspond to the signal. The system compensates for background noise by using the background amplitude level, described above, to alter the audio signal amplitudes relative to the acoustic model amplitudes.

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Newton, MA, United States of America

Jed M Roberts