Acoustic model creating method, acoustic model creating apparatus, acoustic model creating program, and speech recognition apparatus
First Claim
1. An acoustic model creating method of optimizing Gaussian distribution numbers for respective states constituting an HMM (hidden Markov Model) for each state, and thereby creating an HMM having optimized Gaussian distribution numbers, the acoustic model creating method comprising:
- incrementing a Gaussian distribution number step by step according to a specific increment rule for each state in plural HMM'"'"'s, and setting each state to a specific Gaussian distribution number;
creating matching data by matching each state in respective HMM'"'"'s, which has been set to the specific Gaussian distribution number in the distribution number setting, to training speech data;
finding, according to a Minimum Description Length criterion, a description length of each state in respective HMM'"'"'s having a Gaussian distribution number at a present time to be outputted as a present time description length, and finding, according to the Minimum Description Length criterion, a description length of each state in respective HMM'"'"'s having a Gaussian distribution number immediately preceding the present time to be outputted as an immediately preceding description length, with use of the matching data created in the matching data creating; and
comparing the present time description length with the immediately preceding description length in size, both of which are calculated in the description length calculating, and setting an optimum Gaussian distribution number for each state in respective HMM'"'"'s on a basis of a comparison result.
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Abstract
Exemplary embodiments of the invention enhance the recognition ability by optimizing the distribution numbers for respective states that constitute an HMM (for example, a syllable HMM). Exemplary embodiments provide a distribution number setting device to increment the distribution number step by step for each state in an HMM; an alignment data creating unit to create alignment data by matching each state having been set to a specific distribution number to training speech data; a description length calculating unit to find, according to the Minimum Description Length criterion, a description length of each state in an HMM having the present time distribution number and a description length of each state in an HMM having the immediately preceding distribution number, with the use of the alignment data; and an optimum distribution number determining device to set an optimum distribution number to each state on the basis of the size of the description length found for each state in the HMM having the present time distribution number and the description length found for each state in the HMM having the immediately preceding distribution number.
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Citations
14 Claims
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1. An acoustic model creating method of optimizing Gaussian distribution numbers for respective states constituting an HMM (hidden Markov Model) for each state, and thereby creating an HMM having optimized Gaussian distribution numbers, the acoustic model creating method comprising:
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incrementing a Gaussian distribution number step by step according to a specific increment rule for each state in plural HMM'"'"'s, and setting each state to a specific Gaussian distribution number;
creating matching data by matching each state in respective HMM'"'"'s, which has been set to the specific Gaussian distribution number in the distribution number setting, to training speech data;
finding, according to a Minimum Description Length criterion, a description length of each state in respective HMM'"'"'s having a Gaussian distribution number at a present time to be outputted as a present time description length, and finding, according to the Minimum Description Length criterion, a description length of each state in respective HMM'"'"'s having a Gaussian distribution number immediately preceding the present time to be outputted as an immediately preceding description length, with use of the matching data created in the matching data creating; and
comparing the present time description length with the immediately preceding description length in size, both of which are calculated in the description length calculating, and setting an optimum Gaussian distribution number for each state in respective HMM'"'"'s on a basis of a comparison result. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 14)
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12. An acoustic model creating apparatus that optimizes Gaussian distribution numbers for respective states constituting an HMM (hidden Markov Model) for each state, and thereby creates an HMM having optimized Gaussian distribution numbers, the acoustic model creating apparatus comprising:
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a distribution number setting device to increment a Gaussian distribution number step by step according to a specific increment rule for each state in plural HMM'"'"'s, and setting each state to a specific Gaussian distribution number;
a matching data creating device to create matching data by matching each state in respective HMM'"'"'s, which has been set to the specific Gaussian distribution number by the distribution number setting device, to training speech data;
a description length calculating device to find, according to a Minimum Description Length criterion, a description length of each state in respective HMM'"'"'s having a Gaussian distribution number at a present time to be outputted as a present time description length, and finding, according to the Minimum Description Length criterion, a description length of each state in respective HMM'"'"'s having a Gaussian distribution number immediately preceding the present time to be outputted as an immediately preceding description length, with the use of the matching data created by the matching data creating device; and
an optimum distribution number determining device to compare the present time description length with the immediately preceding description length in size, both of which are calculated by the description length calculating device, and to set an optimum Gaussian distribution number for each state in respective HMM'"'"'s on the basis of a comparison result.
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13. An acoustic model creating program for use with a computer to optimize Gaussian distribution numbers for respective states constituting an HMM (hidden Markov Model) for each state, and thereby to create an HMM having optimized Gaussian distribution numbers, said acoustic model creating program comprising:
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a distribution number setting procedural program for incrementing a Gaussian distribution number step by step according to a specific increment rule for each state in plural HMM'"'"'s, and setting each state to a specific Gaussian distribution number;
a matching data creating procedural program for creating matching data by matching each state in respective HMM'"'"'s, which has been set to the specific Gaussian distribution number in the distribution number setting procedure, to train speech data;
a description length calculating procedural program for finding, according to a Minimum Description Length criterion, a description length of each state in respective HMM'"'"'s having a Gaussian distribution number at a present time to be outputted as a present time description length, and finding, according to said Minimum Description Length criterion, a description length of each state in respective HMM'"'"'s having a Gaussian distribution number immediately preceding the present time to be outputted as an immediately preceding description length, with the use of the matching data created in said matching data creating procedural step; and
an optimum distribution number determining procedural program for comparing the present time description length with the immediately preceding description length in size, both of which are calculated in the description length calculating procedure, and setting an optimum Gaussian distribution number for each state in respective HMM'"'"'s on the basis of a comparison result.
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Specification