Granted Patent B2

US 6,895,375 · App. 09/971,375 · Granted May 17, 2005

Abstract

Claims (794)

1. A system for generating a wideband signal from a narrowband signal, the system comprising:

a linear predictive coefficient module that computes narrowband coefficients;

an area coefficient module that computes area coefficients using the narrowband coefficients;

an area shifted-interpolation module the performs a shifted-interpolation of the area coefficients; and

a module that transforms the shift-interpolated area coefficients into wideband linear predictive coefficients used for generating a wideband signal y wb .

2. The system for generating a wideband signal of claim 1 , further comprising a synthesis module for generating the wideband signal y wb using the wideband linear predictive coefficients.

3. The system for generating a wideband signal of claim 1 , wherein the linear predictive coefficient module computes narrowband parcors and the area coefficient module computes area coefficients using the narrowband parcors.

4. The system for generating a wideband signal of claim 1 , wherein the area coefficient module computes M nb area coefficient using the following equation:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

⁢

,

1

,

where A 1 corresponds to a cross-section at the lips, A M nb +1 correspond to cross-sections of the vocal tract at the glottis opening and r i are reflection coefficients.

5. The system for generating a wideband signal of claim 1 , wherein the area shifted-interpolation module interpolates using a linear first order polynomial interpolation scheme.

6. The system for generating a wideband signal of claim 1 , wherein the area shifted-interpolation module interpolates using a cubic spline interpolation scheme.

7. The system for generating a wideband signal of claim 1 , wherein the area shifted-interpolation module interpolates using a fractal interpolation scheme.

8. The system for generating a wideband signal of claim 1 , wherein the area shifted-interpolation module interpolates by a factor of 2, with a ¼ sampling interval shift.

9. The system for generating a wideband signal of claim 1 , wherein the area shifted-interpolation module interpolates by a factor of 4 followed by a single sampling interval shift and decimating by a factor of 2.

10. A system for generating a wideband signal from a narrowband signal, the system comprising:

a linear predictive coefficient module that computes narrowband coefficients;

an area coefficient module that computes area coefficients using the narrowband coefficients;

an area shifted-interpolation module the performs a shifted-interpolation of the area coefficients;

a module that transforms the shift-interpolated area coefficients into wideband linear predictive coefficients;

a synthesis module for generating a wideband signal y wb using the wideband linear predictive coefficients;

a filter for high-pass filtering the wideband signal y wb to generate a highband signal; and

a summer that combines the highband signal with the narrowband signal interpolated to a wideband sample rate to produce a wideband signal ŝ wb .

11. A system for generating a wideband signal from a narrowband signal, the system comprising:

(1) a narrowband processing module that produces a wideband excitation signal;

(2) a wideband module that produces wideband linear predictive coefficients (LPCs) a i wb , the wideband module performing a method comprising:

(a) computing partial correlation coefficients r i (parcors) from the narrowband signal;

(b) computing M nb area coefficients according to the following equation:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

⁢

,

1

,

 where A 1 corresponds to the cross-section at lips and A M nb +1 corresponds to the cross-section at a glottis opening;

(c) extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation;

(d) computing wideband parcors r i wb from the M wb area coefficients according to the following:

r

i

wb

=

A

i

wb

-

A

i

+

1

wb

A

i

wb

+

A

i

+

1

wb

,

⁢

i

=

1

,

2

,

…

⁢

,

M

wb

;

 and

(e) computing wideband linear predictive coefficients (LPCs) a i wb from the wideband parcors r i wb ; and

(3) a synthesizing module that synthesizes a wideband signal y wb from the wideband LPCs a i wb and the wideband excitation signal; and

(4) a summer that combines the synthesized wideband signal y wb and the narrowband signal interpolated to the wideband sample rate to generate a wideband signal ŝ wb .

12. A system for generating a wideband signal from a narrowband signal, the narrowband signal having narrowband coefficients computed from a linear prediction analysis, the system comprising:

an area coefficient module that computes area coefficients associated with the narrowband coefficients;

an area shifted-interpolation module the performs a shifted interpolation of the area coefficients; and

a transformation module that transforms the shifted-interpolated area coefficients into wideband coefficients used to synthesize a wideband signal y wb .

13. The system for generating a wideband signal from a narrowband signal of claim 12 , further comprising a synthesis module for synthesizing the wideband signal y wb using the wideband coefficients.

14. The system for generating a wideband signal from a narrowband signal of claim 13 , the system further comprising:

a filter for high-pass filtering the wideband signal y wb to generate a highband signal; and

a summer that combines the highband signal with the narrowband signal interpolated to a wideband sample rate to generate a wideband signal ŝ wb .

15. A system for generating a wideband signal from a narrowband signal, the narrowband signal having narrowband coefficients computed from a linear prediction analysis, the system comprising:

a log-area coefficient module that computes log-area coefficients associated with the narrowband coefficients;

an area shifted-interpolation module the performs a shifted-interpolation of the log-area coefficients; and

a transformation module that transforms the shifted-interpolated log-area coefficients into wideband coefficients used to synthesize a wideband signal y wb .

16. The system for generating a wideband signal from a narrowband signal of claim 15 , the system further comprising a synthesis module for synthesizing the wideband signal y wb using the wideband coefficients.

17. The system for generating a wideband signal from a narrowband signal of claim 16 , the system further comprising:

a filter for high-pass filtering the wideband signal y wb to generate a highband signal; and

a summer that combines the highband signal y wb with the narrowband signal interpolated to a wideband sample rate to generate a wideband signal ŝ wb .

18. The system for generating a wideband signal from a narrowband signal of claim 15 , wherein the log-area coefficient module computes M nb log-area coefficients using the equation below and computing their logarithmic values:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

⁢

,

1

,

where A 1 corresponds to a cross-section at the lips, A M nb +1 correspond to cross-sections of the vocal tract at the glottis opening and r i are reflection coefficients.

19. The system for generating a wideband signal from a narrowband signal of claim 15 , wherein the log-area coefficient module interpolates the log-area coefficients using a linear first order polynomial interpolation scheme.

20. The system for generating a wideband signal from a narrowband signal of claim 15 , wherein the log-area coefficient module interpolates the log-area coefficients using a cubic spline interpolation scheme.

21. The system for generating a wideband signal from a narrowband signal of claim 15 , wherein the log-area coefficient module interpolates the log-area coefficients using a fractal interpolation scheme.

22. The system for generating a wideband signal from a narrowband signal of claim 15 , wherein the log-area coefficient module interpolates the log-area coefficients by a factor of 2, with a ¼ sample shift.

23. The system for generating a wideband signal from a narrowband signal of claim 15 , wherein the log-area coefficient module interpolates the log-area coefficients by a factor of 4 followed by a single sample shift and decimating by a factor of 2.

24. A system for generating a wideband signal from a narrowband signal, the system comprising:

(1) a module for processing the narrowband signal comprising:

(a) a signal interpolation module producing an interpolated narrowband signal;

(b) an inverse filter that filters the interpolated narrowband signal; and

(c) a nonlinear operation module that generates an excitation signal from the filtered interpolated narrowband signal;

(2) a module for producing wideband coefficients comprising:

(a) a linear predictive analysis module that produces M nb narrowband coefficients associated with the narrowband signal;

(b) an area parameter module that computes area parameters using the M nb narrowband coefficients;

(c) a shifted-interpolation module that computes shift-interpolated area parameters from the area parameters; and

(d) a module that computes M wb wideband coefficients from the shift-interpolated area parameters; and

(3) a synthesis module that receives the M wb wideband coefficients and the excitation signal to synthesize a wideband signal y wb .

25. The system for generating a wideband signal from a narrowband signal of claim 24 , the system further comprising:

(4) a filter and gain module for filtering the wideband signal y wb to generate a highband signal; and

(5) a summer for combining the highband signal and the narrowband signal interpolated to a wideband sample rate to generate a wideband signal ŝ wb .

26. The system for generating a wideband signal from a narrowband signal of claim 25 , wherein the module for producing wideband coefficients further produces narrowband parcors from the M nb narrowband coefficients, and computes the M wb wideband coefficients from wideband parcors generated from the wideband area coefficients.

27. The system for generating a wideband signal from a narrowband signal of claim 25 , wherein the M nb narrowband area coefficients A i nb , i=1, 2, . . . , M nb are generated using the following:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

⁢

,

1

,

where A 1 corresponds to a cross-section at lips, A M nb +1 and corresponds to a cross-section of a vocal tract at a glottis opening.

28. The system for generating a wideband signal from a narrowband signal of claim 27 , wherein the wideband parcors using the M wb area coefficients are generated according to the following:

r

i

wb

=

A

i

wb

-

A

i

+

1

wb

A

i

wb

+

A

i

+

1

wb

,

⁢

i

=

1

,

2

,

…

⁢

,

M

wb

.

29. A system for generating a wideband signal from a narrowband signal, the system comprising:

(1) a narrowband signal module that produces an interpolated narrowband signal at a wideband sampling rate; and

(2) a wideband signal module that generates a wideband signal y wb according to a method comprising:

(a) computing area parameters from narrowband linear predictive coefficients (LPCs) associated with the narrowband signal;

(b) interpolating the area parameters;

(c) converting the interpolated area parameters into wideband linear predictive coefficients; and

(d) synthesizing the wideband signal y wb using the wideband linear predictive coefficients.

30. The system for generating a wideband signal from a narrowband signal of claim 29 , wherein the method used by the wideband signal module to generate the wideband signal further comprises:

(e) highpass filtering the wideband signal y wb to form a highband signal; and

(f) combining the highband signal and the interpolated narrowband signal to generate a wideband signal ŝ wb .

31. The system for generating a wideband signal from a narrowband signal of claim 29 , wherein the wideband signal module further produces wideband linear predictive coefficients by:

computing narrowband parcors using recursion;

computing M nb area coefficients using the narrowband parcors, wherein the area parameters are the M nb area coefficients;

extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation, wherein the interpolated are parameters are the M wb area coefficients;

computing wideband parcors using the M wb area coefficients; and

computing the wideband LPCs from the wideband parcors.

32. A system for generating a wideband signal from a narrowband signal, the system comprising:

(1) a narrowband signal module that produces an interpolated narrowband signal at a wideband sampling rate and produces a wideband excitation signal from the narrowband signal; and

(2) a wideband signal module that generates a wideband signal y wb according to a method comprising:

(a) computing partial correlation coefficients r i (parcors) from the narrowband signal;

(b) computing M nb area coefficients according to the following equation:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

,

1

,

 where A 1 corresponds to the cross-section at lips and A M nb +1 corresponds to the cross-section at a glottis opening;

(c) computing M nb log-area coefficients by applying a natural-log operator to the M nb area coefficients;

(d) extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation;

(e) converting the M wb log-area coefficients into M wb area coefficients;

(f) computing wideband parcors r i wb from the M wb area coefficients according to the following:

r

i

wb

=

A

i

wb

-

A

i

+

1

wb

A

i

wb

+

A

i

+

1

wb

,

⁢

i

=

1

,

2

,

…

,

M

wb

;

(g) computing wideband linear predictive coefficients (LPCs) a i wb from the wideband parcors r i wb ; and

(h) synthesizing the wideband signal y wb from the wideband LPCs a i wb and the wideband excitation signal.

33. A system for generating a wideband signal from a narrowband signal, the system comprising:

(1) a narrowband signal module that produces an interpolated narrowband signal at a wideband sampling rate and produces a wideband excitation signal from the narrowband signal; and

(2) a wideband signal module that generates a wideband signal y wb according to a method comprising:

(a) computing partial correlation coefficients r i (parcors) from the narrowband signal;

(b) computing M nb area coefficients according to the following equation:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

,

1

,

 where A 1 corresponds to the cross-section at lips and A M nb + corresponds to the cross-section at a glottis opening;

(c) computing M nb log-area coefficients by applying a natural-log operator to the M nb area coefficients;

(d) extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation;

(e) converting the M wb log-area coefficients into M wb area coefficients;

(f) computing wideband parcors r i wb from the M wb area coefficients according to the following:

r

i

wb

=

A

i

wb

-

A

i

+

1

wb

A

i

wb

+

A

i

+

1

wb

,

⁢

i

=

1

,

2

,

…

,

M

wb

;

(g) computing wideband linear predictive coefficients (LPCs) a i wb from the wideband parcors r i wb ; and

(h) synthesizing a wideband signal y wb from the wideband LPCs a i wb and the wideband excitation signal;

(i) highpass filtering the wideband signal y wb to form a highband signal S hb ; and

(j) generating a wideband signal ŝ wb by summing the highband signal S hb and the interpolated narrowband signal.

34. The system for generating a wideband signal from a narrowband signal of claim 33 , wherein the narrowband signal module produces the wideband excitation signal from the narrowband signal according to the following method:

(a) performing linear prediction on the narrowband signal to find a i wb LP coefficients;

(b) interpolating the narrowband signal to produce an upsampled narrowband signal;

(c) producing a narrowband residual signal {tilde over (r)} nb by inverse filtering the upsampled interpolated narrowband signal using a transfer function associated with the a i wb LP coefficients; and

(d) generating the wideband excitation signal from the narrowband residual signal {tilde over (r)} nb .

35. A system for producing a wideband signal from a narrowband signal, the system comprising:

a module that computes M nb area coefficients from the narrowband signal;

a module that interpolates the M nb area coefficients into M wb area coefficients; and

a module that generates a wideband signal y wb using the M wb area coefficients.

36. The system for producing a wideband signal from a narrowband signal of claim 35 , the system further comprising:

a module that generates a wideband signal ŝ wb by combining the wideband signal y wb with the narrowband signal interpolated to the highband sampling rate.

37. A computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal according to the following method:

(1) computing partial correlation coefficients (parcors) from the narrowband signal;

(2) computing M nb area coefficients using the parcors;

(3) extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation;

(4) computing highband parcors from the M wb area coefficients;

(5) converting the M wb area coefficients into highband LPCs using the highband parcors; and

(6) synthesizing a wideband signal y wb using the highband LPCs and a wideband excitation signal generated from the narrowband signal.

38. The computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal of claim 37 , the method further comprising:

(7) filtering the wideband signal y wb to generate a highband signal; and

(8) summing the highband signal and the narrowband signal interpolated to the wideband sample rate to generate a wideband signal ŝ wb .

39. The computer-readable storage medium of claim 37 , wherein the number of M wb area coefficients is two times the number of M nb area coefficients.

40. A computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal, the method comprising:

(1) computing partial correlation coefficients (parcors) from the narrowband signal;

(2) computing M nb area coefficients using the parcors;

(3) computing M nb log-area coefficients using the M nb area coefficients;

(4) extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation;

(5) applying exponentiation to compute M wb area coefficients;

(6) computing wideband parcors from the M wb area coefficients;

(7) converting the M wb area coefficients into wideband LPCs using the wideband parcors; and

(8) synthesizing a wideband signal y wb using the wideband LPCs and an excitation signal generated from the narrowband signal.

41. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 40 , the method further comprising:

(9) filtering the wideband signal y wb to generate a highband signal;

(10) combining the highband signal and the narrowband signal interpolated to the wideband sample rate to generate a wideband signal ŝ wb .

42. A computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal, the method receiving narrowband data associated with a narrowband signal, the method comprising:

computing M nb area coefficients using the narrowband data;

extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation; and

synthesizing a wideband signal y wb using wideband coefficients generated from the M wb area coefficients and an excitation signal.

43. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 42 , the method further comprising:

filtering the wideband signal y wb to generate a highband signal; and

generating a wideband signal ŝ wb by combining the highband signal and the narrowband signal interpolated to the wideband sample rate.

44. The computer-readable storage medium of claim 42 , wherein the data associated with the M wb area coefficients used to synthesize the wideband signal y wb further comprises wideband parcors computed from the interpolated M wb area coefficients and wideband linear predictive coefficients computed from the wideband parcors.

45. The computer-readable storage medium of claim 42 , wherein the excitation signal used to synthesize the wideband signal y wb further comprises a wideband excitation signal generated from a narrowband residual signal.

46. The computer-readable storage medium of claim 42 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises interpolating by a factor of 2 with a ¼ sample shift.

47. The computer-readable storage medium of claim 42 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises interpolating by a factor of 4 followed by a single sample shift and decimating by a factor of 2.

48. A computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal, the method comprising:

(1) generating a wideband excitation signal from the narrowband signal;

(2) computing M nb area coefficients from the narrowband signal;

(3) extracting M wb area coefficients from the M nb area coefficients using interpolation;

(4) computing wideband linear predictive coefficients (LPCs) using the M wb area coefficients; and

(5) synthesizing a wideband signal y wb from the wideband LPCs a i wb and the wideband excitation signal.

49. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 48 , wherein generating a wideband excitation signal further comprises:

(a) performing linear prediction on the narrowband signal to find a i wb LP coefficients;

(b) interpolating the narrowband signal to produce an upsampled narrowband signal;

(c) producing a narrowband residual signal {tilde over (r)} nb by inverse filtering the upsampled interpolated narrowband signal using a transfer function associated with the a i wb LP coefficients; and

(d) generating the wideband excitation signal from the narrowband residual signal {tilde over (r)} nb .

50. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 48 , the method further comprising:

(6) highpass filtering the wideband signal y wb to produce a highband signal; and

(7) generating a wideband signal ŝ wb by summing the highband signal and the narrowband signal interpolated to the wideband sample rate.

51. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 48 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises interpolating by a factor of 2 with a ¼ sample shift.

52. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 48 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises interpolating by a factor of 4 followed by a single sample shift and decimating by a factor of 2.

53. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 48 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises using a first order linear shifted-interpolation.

54. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 48 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises using cubic-spline interpolation.

55. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 48 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises using fractal interpolation.

56. A computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal, the instructions controlling the computer device to perform the steps of:

(1) producing a wideband excitation signal from the narrowband signal;

(2) computing partial correlation coefficients r i (parcors) from the narrowband signal;

(3) computing M nb area coefficients according to the following equation:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

,

1

,

 where A 1 corresponds to the cross-section at lips and A M nb +1 corresponds to the cross-section at a glottis opening;

(4) computing M nb log-area coefficients by applying a natural-log operator to the M nb area coefficients;

(5) extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation;

(6) converting the M wb log-area coefficients into M wb area coefficients;

(7) computing wideband parcors r i wb from the M wb area coefficients according to the following:

r

i

wb

=

A

i

wb

-

A

i

+

1

wb

A

i

wb

+

A

i

+

1

wb

,

⁢

i

=

1

,

2

,

…

,

M

wb

;

(8) computing wideband linear predictive coefficients (LPCs) a i wb from the wideband parcors r i wb ; and

(9) synthesizing a wideband signal y wb from the wideband LPCs a i wb and the wideband excitation signal.

57. The computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal of claim 56 , the instructions controlling the computer device to further perform the steps of:

(10) highpass filtering the wideband signal y wb to form a highband signal S hb ; and

(11) generating a wideband signal ŝ wb by summing the highband signal S hb and the narrowband signal interpolated to the wideband sample rate.

58. The computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal of claim 57 , wherein extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation further comprises using a linear first order polynomial interpolation scheme.

59. The computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal of claim 57 , wherein extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation further comprises using a cubic spline interpolation scheme.

60. The computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal of claim 57 , wherein extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation further comprises using a fractal interpolation scheme.

61. A computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal, the method comprising:

(1) computing partial correlation coefficients r i (parcors) from the narrowband signal;

(2) computing M nb area coefficients according to the following equation:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

,

1

,

 where A 1 corresponds to the cross-section at lips and A M nb +1 corresponds to the cross-section at a glottis opening;

(3) computing M nb log-area coefficients;

(4) extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation;

(5) computing M wb area coefficients from the M nb log-area coefficients;

(6) computing wideband parcors r i wb from the M wb area coefficients according to the following:

r

i

wb

=

A

i

wb

-

A

i

+

1

wb

A

i

wb

+

A

i

+

1

wb

,

⁢

i

=

1

,

2

,

…

,

M

wb

;

(7) computing wideband linear predictive coefficients (LPCs) a i wb from the wideband parcors r i wb ; and

(8) synthesizing a wideband signal y wb from the wideband LPCs and an excitation signal.

62. The computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal of claim 61 , the method further comprising:

(9) generating a wideband signal ŝ wb by combining the wideband signal y wb and the narrowband signal interpolated to the wideband sample rate.

63. The computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal of claim 62 , wherein extracting M wb , log-area coefficients from the M nb log-area coefficients using shifted-interpolation further comprises using a linear first order polynomial interpolation scheme.

64. The computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal of claim 62 , wherein extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation further comprises using a cubic spline interpolation scheme.

65. The computer-readable storage medium storing instructions for controlling a computer device to produce a wideband signal from a narrowband signal of claim 62 , wherein extracting M wb log-area coefficients from the M nb log-area coefficients using shifted-interpolation further comprises using a fractal interpolation scheme.

66. A computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal, the method comprising:

(1) computing M nb area coefficients from the narrowband signal;

(2) extracting M nb area coefficients from the M nb area coefficients using interpolation;

(3) computing wideband linear predictive coefficients (LPCs) using the M wb area coefficients; and

(4) synthesizing a wideband signal y wb from the wideband LPCs a i wb and highpass filtered white noise.

67. A wideband signal generated according to a method of extending the bandwidth of a narrowband signal, the method comprising:

(1) computing M nb area coefficients from the narrowband signal;

(2) extracting M wb area coefficients from the M nb area coefficients using interpolation; and

(3) synthesizing a wideband signal y wb using wideband coefficients processed from data associated with the M nb area coefficients and an excitation signal.

68. The wideband signal generated according to a method of extending the bandwidth of a narrowband signal of claim 67 , the method further comprising generating the excitation signal from the narrowband signal by:

(a) performing linear prediction on the narrowband signal to find a i wb LP coefficients;

(b) interpolating the narrowband signal to produce an upsampled narrowband signal;

(c) producing a narrowband residual signal {tilde over (r)} nb by inverse filtering the upsampled interpolated narrowband signal using a transfer function associated with the a i wb LP coefficients; and

(d) generating the wideband excitation signal from the narrowband residual signal {tilde over (r)} nb .

69. The wideband signal generated according to a method of extending the bandwidth of a narrowband signal of claim 67 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises interpolating by a factor of 2 with a ¼ sample shift.

70. The wideband signal generated according to a method of extending the bandwidth of a narrowband signal of claim 67 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises interpolating by a factor of 4 followed by a single sample shift and decimation by a factor of 2.

71. The wideband signal generated according to a method of extending the bandwidth of a narrowband signal of claim 67 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises using a first order linear shifted-interpolation.

72. The wideband signal generated according to a method of extending the bandwidth of a narrowband signal of claim 67 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises using cubic-spline interpolation.

73. The wideband signal generated according to a method of extending the bandwidth of a narrowband signal of claim 67 , wherein extracting M wb area coefficients from the M nb area coefficients using shifted-interpolation further comprises using fractal interpolation.

74. A wideband signal generated according to a method of extending the bandwidth of a narrowband signal, the method comprising:

(1) computing M nb area coefficients from the narrowband signal;

(2) extracting M wb area coefficients from the M nb area coefficients using interpolation;

(3) synthesizing a wideband signal y wb using wideband coefficients processed from data associated with the M nb area coefficients and an excitation signal generated from the narrowband signal;

(4) highpass filtering the wideband signal y wb to generate a highband signal; and

(5) generating a wideband signal ŝ wb by combining the highband signal and the narrowband signal interpolated to the wideband sample rate.

75. A wideband signal generated according to a method of extending the bandwidth of a narrowband signal, the narrowband signal having associated parcors, the method comprising:

(1) computing M nb area coefficients from the narrowband parcors;

(2) obtaining M wb area coefficients using interpolation;

(3) synthesizing a wideband signal y wb from the M wb area coefficients;

(4) filtering the wideband signal y wb to generate a highband signal; and

(5) generating a wideband signal ŝ wb by combining the highband signal and the narrowband signal interpolated to the wideband sample rate.

76. The wideband signal generated according to a method of extending the bandwidth of a narrowband signal of claim 75 , wherein the area coefficients computed relate the discrete acoustic tube model.

77. A wideband signal generated from a narrowband signal according to a method comprising:

(1) computing M nb area coefficients from the narrowband signal;

(2) computing M nb log-area coefficients from the M nb area coefficients;

(3) interpolating the M nb log-area coefficients into M wb log-area coefficients;

(4) converting the M wb log-area coefficients into M wb area coefficients; and

(5) synthesizing a wideband signal y wb using the M wb area coefficients and white noise.

78. A wideband signal generated from a narrowband signal according to a method comprising:

(1) computing M nb area coefficients from the narrowband signal;

(2) computing M nb log-area coefficients from the M nb area coefficients;

(3) interpolating the M nb log-area coefficients into M wb log-area coefficients;

(4) converting the M wb log-area coefficients into M wb area coefficients;

(5) synthesizing a wideband signal y wb using the M wb area coefficients and an excitation signal;

(6) generating a highband signal by highpass filtering the wideband signal y wb ; and

(7) combining the highband signal with the narrowband signal interpolated to the wideband sample rate to generate a wideband signal ŝ wb .

79. The wideband signal of claim 78 , wherein computing M nb area coefficients further comprises computing M nb area coefficients using the following equation:

A

i

=

1

+

r

i

1

-

r

i

⁢

A

i

+

1

;

⁢

i

=

M

nb

,

M

nb

-

1

,

…

,

1

,

where A 1 corresponds to a cross-section at the lips, A M nb +1 corresponds to a cross-section at the glottis opening and r i are reflection coefficients.

80. The wideband signal of claim 78 , wherein interpolating the M nb log-area coefficients into M wb log-area coefficients further comprises interpolating, using a linear first order polynomial interpolation scheme.

81. The wideband signal of claim 78 , wherein interpolating the M nb log-area coefficients further comprises interpolating using a cubic spline interpolation scheme.

82. The wideband signal of claim 78 , wherein interpolating the M nb log-area coefficients further comprises interpolating using a fractal interpolation scheme.

83. The wideband signal of claim 78 , wherein interpolating the M nb log-area coefficients further comprises interpolating by a factor of 2, with a ¼ sample shift.

84. The wideband signal of claim 78 , wherein interpolating the M nb log-area coefficients further comprises interpolating by a factor of 4 followed by a single sample shift and decimating by a factor of 2.

85. A system for generating a wideband signal from a narrowband signal, the system comprising:

a module for computing M nb log-area coefficients by applying a log operator to M nb area coefficients generated from the narrowband signal;

a module for extracting M wb log-area coefficients from the M nb log-area coefficients using interpolation; and

a module for generating a wideband signal using M wb area coefficients generated from the M wb log-area coefficients.

86. The system for generating a wideband signal from a narrowband signal of claim 85 , wherein extracting the M nb log-area coefficients using interpolation further comprises interpolating by a factor of 4 followed by a single sampling interval shift and decimating by a factor of 2.

87. A computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal, the method comprising:

computing M nb area coefficients from the narrowband signal;

interpolating the M nb area coefficients into M wb area coefficients; and generating the wideband signal using the M wb area coefficients.

88. The computer-readable medium of claim 87 , wherein interpolating the M nb area coefficients further comprises interpolating by a factor of 4 followed by a single sampling interval shift and decimating by a factor of 2.

89. A computer-readable storage medium storing a method for controlling a computer device to produce a wideband signal from a narrowband signal, the method comprising:

computing M nb log-area coefficients by applying a log operator to M nb area coefficients generated from the narrowband signal;

extracting M wb log-area coefficients from the M nb log-area coefficients using interpolation; and

generating a wideband signal using M wb area coefficients generated from the M wb log-area coefficients.

90. The computer-readable medium of claim 89 , wherein extracting the M nb log-area coefficients using interpolation further comprises interpolating by a factor of 4 followed by a single sampling interval shift and decimating by a factor of 2.

91. A wideband signal generated from a narrowband signal according to a method comprising:

computing M nb area coefficients from the narrowband signal;

interpolating the M nb area coefficients into M wb area coefficients; and

generating the wideband signal using the M wb area coefficients.

92. The wideband signal of claim 91 , wherein interpolating the M nb area coefficients further comprises interpolating by a factor of 4 followed by a single sampling interval shift and decimating by a factor of 2.

93. A wideband signal generated from a narrowband signal according to a method comprising:

computing M nb log-area coefficients by applying a log operator to M nb area coefficients generated from the narrowband signal;

extracting M wb log-area coefficients from the M nb log-area coefficients using interpolation; and

generating a wideband signal using M wb area coefficients generated from the M wb log-area coefficients.

94. The wideband signal of claim 93 , wherein extracting the M nb log-area coefficients using interpolation further comprises interpolating by a factor of 4 followed by a single sampling interval shift and decimating by a factor of 2.

Assignments (11)