Method and apparatus for performing observation probability calculations

• US 20040002861A1
• Filed: 06/20/2003
• Published: 01/01/2004
• Est. Priority Date: 06/28/2002
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Sung-Jae, Kim, Tae-Su, Park, Hyun-Woo, Min, Byung-Ho, Jang, Ho-Rang, Hong, Keun-Cheol
• Granted Patent: US 7,356,466 B2
• Time in Patent Office: Days
• US Class Current: 704/240
• CPC Class Codes: G10L 15/144 Training of HMMs

Abstract

A method and apparatus for calculating an observation probability includes a first operation unit that subtracts a mean of a first plurality of parameters of an input voice signal from a second parameter of an input voice signal, and multiplies the subtraction result to obtain a first output. The first output is squared and accumulated N times in a second operation unit to obtain a second output. A third operation unit subtracts a given weighted value from the second output to obtain a third output, and a comparator stores the third output for a comparator stores the third output in order to extract L outputs therefrom, and stores the L extracted outputs based on an order of magnitude of the extracted L outputs.

Claims

1. An observation probability calculation apparatus comprising:

a first operation unit subtracting a mean of parameters extracted from representative phonemes from a parameter extracted from an input voice signal and multiplying the result of the subtraction by a distribution degree (dispersion) of the mean to obtain a first output, wherein the distribution degree (dispersion) is called Precision;

a second operation unit squaring the first output of the first operation unit and accumulating the result of the squaring N times to obtain a second output;

a third operation unit subtracting a predetermined weighted value from the second output of the second operation unit to obtain a third output; and

a comparator storing the third output of the third operation unit, extracting L outputs from the outputs of the third operation unit, and storing the extracted L outputs in order of magnitude.

2. The apparatus of claim 1, wherein the comparator comprises:

first through L-th registers storing the extracted L outputs in order of magnitude; and

first through L-th index registers storing an order in which the extracted L outputs stored in the first through L-th registers are generated.

3. The apparatus of claim 2, wherein L is 3.

4. The apparatus of claim 1, further comprising:

a first operation register storing the first output and outputting the stored first output to the second operation unit;

a second operation register storing the second output and outputting the stored second output to the third operation unit; and

a third operation register storing the third output and outputting the stored third output to the comparator.

5. The apparatus of claim 1, further comprising a plurality of registers storing the parameter, mean, distribution degree and weighted value.

6. The apparatus of claim 1, wherein the first and second operation units perform an observation probability calculation (y) in a hidden Markov model algorithm according to:

7. The apparatus of claim 6, wherein the distribution degree is {square root}{square root over (2 var)}.

8. The apparatus of claim 1, wherein the third output is a probabilistic distance between the mean and the parameter extracted from the input voice signal.

9. The apparatus of claim 1, wherein the parameter extracted from the input voice signal is composed of m bits and the mean is composed of m bits.

10. The apparatus of claim 1, wherein N is 13.

21. A voice recognition device including the observation probability calculation apparatus of claim 1.

11. A method of calculating an observation probability, comprising:

subtracting a mean of a first plurality of parameters of an input voice signal from a second parameter extracted from the input voice signal to obtain a result;

multiplying the result to obtain a first output;

squaring the first output; and

accumulating the squared first output to obtain an observation probability value.

12. The method of claim 11, wherein multiplying includes multiplying the result by a distribution degree to obtain the first output.

13. The method of claim 11, wherein the first plurality of parameters are from representative phonemes of the input voice signal.

14. The method of claim 12, further comprising:

subtracting a given weighted value from the observation probability value to obtain a third output, wherein a value of the third output is inversely proportional to the observation probability value.

15. The method of claim 14, wherein

the third output is a probabilistic difference between the mean and the extracted second parameter, and

the observation probability value increases as the probabilistic difference decreases.

16. The method of claim 14, further comprising:

extracting L outputs from the third output; and

selecting an L output having a greatest order of magnitude as a revised observation probability value.

17. The method of claim 16, wherein the revised observation probability value is a greatest probability that a sequence of syllables is recognized as the input voice signal.

18. The method of claim 11, wherein the observation probability value is an accumulation of probabilities, each probability representative of a sequence of syllables.

22. An observation probability calculation apparatus calculating an observation probability value in accordance with the method of claim 11.

19. A method of recognizing a voice signal, comprising:

subtracting a mean of a first plurality of parameters of an input voice signal from a second parameter extracted from the input voice signal to obtain a result; and

multiplying the result to obtain a first output;

squaring the first output;

accumulating the squared first output to obtain a second output;

subtracting a given weighted value from the second output to obtain a third output;

extracting L outputs from the third output; and

selecting an L output having a greatest order of magnitude, the selected L output corresponding to a recognized voice signal.

20. A voice recognition device recognizing a voice signal in accordance with the method of claim 19.