Voicing smoother

1 . A method of correcting errors in a digital speech signal, the method comprising:

receiving a voice bit stream;

generating, from the received voice bit stream, voicing bits of a current frame, voicing bits of a prior frame, and a voicing confidence measure for the current frame;

determining whether the voicing confidence measure is less than a first threshold;

in response to determining that the voicing confidence measure is less than the first threshold:

generating a set of common voicing patterns;

determining whether the current frame matches a voicing pattern in the set of common voicing patterns; and

in response to the current frame failing to match any voicing pattern in the set of common voicing patterns:

resampling voicing bands of the prior frame, so that a number of voicing bands in the resampled prior frame is the same as a number of voicing bands in the current frame;

determining a distance for each of the set of common voicing patterns with respect to the current frame and the prior frame; and

replacing the current frame with a particular voicing pattern in the set of common voicing patterns that has a smallest determined distance.

2 . The method of claim 1 , further comprising:

in response to the current frame matching a voicing pattern in the set of common voicing patterns, determining whether the voicing confidence measure is less than a second threshold that is less than the first threshold.

3 . The method of claim 1 , wherein the set of common voicing patterns comprises {c 0 , . . . , c {tilde over (K)} },

c

i

=

∑

k

=

1

i

+

1

2

K

~

-

k

⁢

0

≤

i

<

K

~

c

K

~

=

0

,

where {tilde over (K)} is the number of voicing bands in the current frame.

4 . The method of claim 1 , wherein the number of voicing bands in the current frame is {tilde over (K)}, and the number of voicing patterns in the set of common voicing patterns is {tilde over (K)}+1.

5 . The method of claim 4 , wherein the set of common voicing patterns is a subset of 2 {tilde over (K)} possible voicing patterns.

6 . The method of claim 1 , wherein resampling the voicing bands of the prior frame further comprises:

generating a voicing decision for each voicing harmonic of the prior frame;

resampling voicing harmonics of the prior frame, so that a number of voicing harmonics in the prior frame is the same as a number of voicing harmonics in the current frame; and

converting the voicing decision for each voicing harmonic of the prior frame to a voicing decision for each voicing band of the prior frame.

7 . The method of claim 1 , wherein the distance is a hamming distance.

8 . The method of claim 7 , wherein the hamming distance is a weighted combination of a first hamming distance between each voicing pattern in the set of common voicing patterns and the prior frame and a second hamming distance between each voicing pattern in the set of common voicing patterns and the current frame.

9 . The method of claim 1 , wherein the voice bit stream is generated by an MBE encoder.

10 . A speech decoder configured to perform operations comprising:

receiving a voice bit stream;

generating, from the received voice bit stream, voicing bits of a current frame, voicing bits of a prior frame, and a voicing confidence measure for the current frame;

determining whether the voicing confidence measure is less than a first threshold;

in response to determining that the voicing confidence measure is less than the first threshold,

generating a set of common voicing patterns;

determining whether the current frame matches a voicing pattern in the set of common voicing patterns;

in response to the current frame failing to match any voicing pattern in the set of common voicing patterns,

resampling voicing bands of the prior frame, so that a number of voicing bands in the resampled prior frame is the same as a number of voicing bands in the current frame;

determining a distance for each of the set of common voicing patterns with respect to the current frame and the prior frame; and

replacing the current frame with a particular voicing pattern in the set of common voicing patterns that has a smallest determined distance.

11 . The speech decoder of claim 10 , the operations further comprising:

in response to the current frame matching a voicing pattern in the set of common voicing patterns, determining whether the voicing confidence measure is less than a second threshold that is less than the first threshold.

12 . The speech decoder of claim 10 , wherein the set of common voicing patterns comprises {c 0 , . . . , c {tilde over (K)} },

c

i

=

∑

k

=

1

i

+

1

2

K

~

-

k

⁢

0

≤

i

<

K

~

c

K

~

=

0

,

where {tilde over (K)} is the number of voicing bands in the current frame.

13 . The speech decoder of claim 10 , wherein the number of voicing bands in the current frame is {tilde over (K)}, and the number of voicing patterns in the set of common voicing patterns is {tilde over (K)}+1.

14 . The speech decoder of claim 13 , wherein the set of common voicing patterns is a subset of 2 {tilde over (K)} possible voicing patterns.

15 . The speech decoder of claim 10 , wherein resampling the voicing bands of the prior frame further comprises:

generating a voicing decision for each voicing harmonic of the prior frame;

resampling voicing harmonics of the prior frame, so that a number of voicing harmonics in the prior frame is the same as a number of voicing harmonics in the current frame; and

converting the voicing decision for each voicing harmonic of the prior frame to a voicing decision for each voicing band of the prior frame.

16 . The speech decoder of claim 10 , wherein the distance is a hamming distance.

17 . The speech decoder of claim 16 , wherein the hamming distance is a weighted combination of a first hamming distance between each voicing pattern in the set of common voicing patterns and the prior frame and a second hamming distance between each voicing pattern in the set of common voicing patterns and the current frame.

18 . The speech decoder of claim 10 , wherein the voice bit stream is generated by an MBE encoder.

19 . A handset or mobile radio comprising the speech decoder of claim 10 .

20 . A base station or console comprising the speech decoder of claim 10 .