System and method for enhanced artificial bandwidth expansion

• US 20050267741A1
• Filed: 05/25/2004
• Published: 12/01/2005
• Est. Priority Date: 05/25/2004
• Status: Active Grant

• Current Assignee: Beijing Xiaomi Mobile Software Co., Ltd. (Xiaomi Corp.)
• Original Assignee: Nokia Corporation
• Inventors: Valve, Paivi, Laaksonen, Laura
• Granted Patent: US 8,712,768 B2
• Time in Patent Office: Days
• US Class Current: 704/209
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

A method, device, system, and computer program product expand narrowband speech signals to wideband speech signals. The method includes determining signal type information from a signal, obtaining characteristics for forming an upper band signal using the determined signal type information, determining signal noise information, using the determined signal noise information to modify the obtained characteristics for forming the upper band signal, and forming the upper band signal using the modified characteristics.

Claims

1. A method for expanding narrowband speech signals to wideband speech signals, the method comprising:

determining signal type information from a signal;

obtaining characteristics for forming an upper band signal using the determined signal type information;

determining signal noise information;

using the determined signal noise information to modify the obtained characteristics for forming the upper band signal; and

forming the upper band signal using the modified characteristics.

2. The method claim 1, wherein determining signal noise information comprises estimating a far-end signal-to-noise ratio using information on energy of a portion of the signal and a background noise level estimate.

3. The method of claim 2, wherein determining signal noise information comprises estimating a near-end signal-to-noise ratio.

4. The method of claim 1, wherein the signal type information is determined based on a signal gradient index, a signal far-end signal-to-noise ratio, and a signal near-end signal-to-noise ratio.

5. The method of claim 4, further comprising classifying the signal into different phoneme groups based on the gradient index and the far-end signal-to-noise ratio.

6. The method of claim 1, further comprising detecting babble noise in the signal.

7. The method of claim 6, wherein the babble noise is detected based on the gradient index, energy information, and a noise level estimate.

8. The method of claim 6, wherein energy information is obtained from an expectance value of the signal to the expectance value of the second derivative of the signal.

9. A communication device configured to receive wideband signals, the device comprising:

an interface that communicates with a wireless network; and

programmed instructions stored in a memory and configured to expand received narrowband signals to wideband signals by adjusting an artificial bandwidth expansion algorithm based on noise conditions.

10. The device of claim 9, wherein the noise conditions comprise a far-end signal-to-noise ratio and a near-end signal-to-noise ratio.

11. The device of claim 9, wherein the programmed instructions are further configured to detect babble noise based on a gradient index, energy information, and a noise level estimate.

12. The device of claim 9, wherein the programmed instructions are implemented with a digital signal processor (DSP).

13. A device in a communication network that expands narrowband speech signals into wideband speech signals, the device comprising:

a narrowband codec that receives narrowband speech signals in a network;

a wideband codec that communicates wideband speech signals to wideband terminals in communication with the network; and

programmed instructions that expand the narrowband speech signals to wideband speech signals by adjusting an artificial bandwidth expansion algorithm based on noise conditions.

14. The device of claim 13, wherein the noise conditions comprise a far-end signal-to-noise ratio and a near-end signal-to-noise ratio.

15. The device of claim 13, wherein the programmed instructions are further configured to detect babble noise based on a gradient index, energy information, and a noise level estimate.

16. A system for expanding narrowband speech signals to wideband speech signals, the system comprising:

means for determining signal type information from a signal;

means for obtaining characteristics for forming an upper band signal using the determined signal type information;

means for determining signal noise information;

means for using the determined signal noise information to modify the obtained characteristics for forming the upper band signal; and

means for forming the upper band signal using the modified characteristics.

17. The system of claim 16, wherein the signal type information is determined based on a signal gradient index, a signal far-end signal-to-noise ratio, and a signal near-end signal-to-noise ratio.

18. The system of claim 16, further comprising detecting babble noise in the signal.

19. A computer program product that expands narrowband speech signals to wideband speech signals, the computer program product comprising:

computer code to;

determine signal type information from a signal;

obtain characteristics for forming an upper band signal using the determined signal type information;

determine signal noise information;

use the determined signal noise information to modify the obtained characteristics for forming the upper band signal; and

form the upper band signal using the modified characteristics.

20. The computer program product of claim 19, wherein the computer code further expands the signal from a narrowband signal to a wideband signal based on signal gradient index, signal far-end signal-to-noise ratio, and signal near-end signal-to-noise ratio.

21. The computer program product of claim 19, wherein the computer code further detects babble noise in the signal.

22. The computer program product of claim 19, wherein the computer code further estimates a near-end signal-to-noise ratio.