Speech coding apparatus and method using classification rules
First Claim
1. A speech coding apparatus comprising:
- means for measuring the value of at least one feature of an utterance during each of a series of successive time intervals to produce a series of feature vector signals representing the feature values;
means for storing a plurality of prototype vector signals, each prototype vector signal having at least one parameter value and having an identification value, at least two prototype vector signals having different identification values;
classification rules means for storing classification rules mapping each feature vector signal from a set of all possible feature vector signals to exactly one of at least two different classes of prototype vector signals, each class containing a plurality of prototype vector signals and each class of prototype vector signals is at least partially different from other classes of prototype vector signals, wherein each class of prototype vector signals contains less than 1/N times the total number of prototype vector signals in all classes, where 5≦
N≦
150;
classifier means for mapping, by the classification rules, a first feature vector signal to a first class of prototype vector signals;
means for comparing the closeness of the feature value of the first feature vector signal to the parameter values of only the prototype vector signals in the first class of prototype vector signals to obtain prototype match scores for the first feature vector signal and each prototype vector signal in the first class; and
means for outputting at least the identification value of at least the prototype vector signal having the best prototype match score as a coded utterance representation signal of the first feature vector signal.
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Abstract
A speech coding apparatus and method uses classification rules to code an utterance while consuming fewer computing resources. The value of at least one feature of an utterance is measured during each of a series of successive time intervals to produce a series of feature vector signals representing the feature values. The classification rules comprise at least first and second sets of classification rules. The first set of classification rules map each feature vector signal from a set of all possible feature vector signals to exactly one of at least two disjoint subsets of feature vector signals. The second set of classification rules map each feature vector signal in a subset of feature vector signals to exactly one of at least two different classes of prototype vector signals. Each class contains a plurality of prototype vector signals. According to the classification rules, a first feature vector signal is mapped to a first class of prototype vector signals. The closeness of the feature value of the first feature vector signal is compared to the parameter values of only the prototype vector signals in the first class of prototype vector signals to obtain prototype match scores for the first feature vector signal and each prototype vector signal in the first class. At least the identification value of at least the prototype vector signal having the best prototype match score is output as a coded utterance representation signal of the first feature vector signal.
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Citations
25 Claims
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1. A speech coding apparatus comprising:
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means for measuring the value of at least one feature of an utterance during each of a series of successive time intervals to produce a series of feature vector signals representing the feature values; means for storing a plurality of prototype vector signals, each prototype vector signal having at least one parameter value and having an identification value, at least two prototype vector signals having different identification values; classification rules means for storing classification rules mapping each feature vector signal from a set of all possible feature vector signals to exactly one of at least two different classes of prototype vector signals, each class containing a plurality of prototype vector signals and each class of prototype vector signals is at least partially different from other classes of prototype vector signals, wherein each class of prototype vector signals contains less than 1/N times the total number of prototype vector signals in all classes, where 5≦
N≦
150;classifier means for mapping, by the classification rules, a first feature vector signal to a first class of prototype vector signals; means for comparing the closeness of the feature value of the first feature vector signal to the parameter values of only the prototype vector signals in the first class of prototype vector signals to obtain prototype match scores for the first feature vector signal and each prototype vector signal in the first class; and means for outputting at least the identification value of at least the prototype vector signal having the best prototype match score as a coded utterance representation signal of the first feature vector signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A speech coding apparatus comprising:
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means for measuring the value of at least one feature of an utterance during each of a series of successive time intervals to produce a series of feature vector signals representing feature values; means for storing a plurality of prototype vector signals, each prototype vector signal having at least one parameter value and having an identification value, at least two prototype vector signals having different identification values; classification rules means for storing classification rules mapping each feature vector signal from a set of all possible feature vector signals to exactly one of at least two different classes of prototype vector signals, each class containing a plurality of prototype vector signals; classifier means for mapping, by the classification rules, a first feature vector signal to a first class of prototype vector signals; means for comparing the closeness of the feature value of the first feature vector signal to the parameter values of only the prototype vector signals in the first class prototype vector signals to obtain prototype match scores for the first feature vector signal and each prototype vector signal in the first class, wherein the closeness of the feature vector signal to the prototype vector signal is one of a Euclidian distance and a Gaussian distance; and means for outputting at least the identification value of at least the prototype vector signal having the best prototype match score as a coded utterance representation signal of the first feature vector signal.
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14. A speech coding method comprising the steps of:
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measuring the value of at least one feature of an utterance during each of a series of successive time intervals to produce a series of feature vector signals representing the feature values; storing a plurality of prototype vector signals, each prototype vector signal having at least one parameter value and having an identification value, at least two prototype vector signals having different identification values; storing classification rules mapping each feature vector signal from a set of all possible feature vector signals to exactly one of at least two different classes of prototype vector signals, each class containing a plurality of prototype vector signals and each class of prototype vector signals is at least partially different from other classes of prototype vector signals, wherein each class of prototype vector signals contains less than 1/N times the total number of prototype vector signals in all classes, where 5≦
N≦
150;mapping, by the classification rules, a first feature vector signal to a first class of prototype vector signals; comparing the closeness of the feature value of the first feature vector signal to the parameter values of only the prototype vector signals in the first class of prototype vector signals to obtain prototype match scores for the first feature vector signal and each prototype vector signal in the first class; and outputting at least the identification value of at least the prototype vector signal having the best prototype match score as a coded utterance representation signal of the first feature vector signal. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A speech coding method comprising the steps of:
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measuring the value of at least one feature of an utterance during each of a series of successive time intervals to produce a series of feature vector signals representing the feature values; storing a plurality of prototype vector signals, each prototype vector signal having at least one parameter vector and having an identification value, at least two prototype vector signals having different identification values; storing classification rules mapping each feature vector from a set of all possible feature vectors to exactly one of at least two different classes of prototype vector signals, each class containing a plurality of prototype vector signals; mapping, by the classification rules, a first feature vector signal to a first class of prototype vector signals; comparing the closeness of the feature vector to the first feature vector signal to the parameter vectors of only the prototype vector signals in the first class of prototype vector signals to obtain prototype match scores for the first feature vector signal and each prototype vector signal in the first class, wherein the comparing step includes comparing the closeness of the feature vector signal to the prototype vector signal using is one of a Euclidian distance and a Gaussian distance; and outputting at least the identification value of at least the prototype vector signal having the best prototype match score as a coded utterance representation signal of the first feature vector signal.
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Specification