Method for detection and correction of errors in speech pitch period estimates
First Claim
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1. A method for detecting and correcting gross errors in pitch period estimates of a speech signal, comprising the steps of:
- determining an average of nonzero values of received pitch period estimates;
accepting a current pitch period estimate if said current pitch period estimate is within a predetermined range of said average; and
correcting said current pitch period estimate if said current pitch period estimate is outside said predetermined range of said average.
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Abstract
A method of detecting and correcting received values of a pitch period estimate of a speech signal for use in a speech coder or the like. An average is calculated of the nonzero values of received pitch period estimate since the previous reset. If a current pitch period estimate is within a range of 0.75 to 1.25 times the average, it is assumed correct, while if not, a correction process is carried out. If correction is required successively for more than a preset number of times, which will most likely occur when the speaker changes, the average is discarded and a new average calculated.
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9 Claims
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1. A method for detecting and correcting gross errors in pitch period estimates of a speech signal, comprising the steps of:
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determining an average of nonzero values of received pitch period estimates; accepting a current pitch period estimate if said current pitch period estimate is within a predetermined range of said average; and correcting said current pitch period estimate if said current pitch period estimate is outside said predetermined range of said average. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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3. The detecting and correcting method of claim 1, wherein said step of correcting said current pitch period estimate comprises:
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(1) if preceding and succeeding pitch period estimates p(i-1) and p(i+1), respectively, are both nonzero, setting p(i) equal to an average of p(i-1) and p(i+1); and (2) if one of p(i-1) and p(i+1) is nonzero, setting p(i) equal to the nonzero one of p(i-1) and p(i+1).
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4. The detecting and correcting method of claim 3, further comprising the step of, if both p(i-1) and p(i+1) are zero, setting p(i) equal to zero.
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5. The detecting and correcting method of claim 4, further comprising the steps of:
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counting a number of consecutive times of correcting said current pitch period estimate p(i) without p(i) being in said predetermined range or p(i) being set equal to zero; and discarding said average and determining a new average when the count exceeds a predetermined limit value.
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6. The detecting and correcting method of claim 4, wherein said predetermined limit value is three.
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7. The detecting and correcting method of claim 1, wherein said step of determining said average comprises recursively calculating:
- ##EQU3## where Nnz is a number of nonzero values of p(i) included in said average.
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8. The detecting and correcting method of claim 1, wherein said step of averaging comprises averaging a predetermined minimum number of nonzero values of said received pitch period estimate before proceeding to said step of accepting a current pitch period estimate.
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9. The detecting and correcting method of claim 8, wherein said predetermined minimum number is eight.
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Specification