Voice enhancement system and method

• US 5,896,449 A
• Filed: 09/25/1996
• Issued: 04/20/1999
• Est. Priority Date: 12/02/1993
• Status: Expired due to Fees

• Current Assignee: Alcatel USA Sourcing L.P. (Nokia Corporation)
• Original Assignee: Alcatel USA Sourcing L.P. (Nokia Corporation)
• Inventors: Tong, Allen Y., Oshidari, Thomas T.
• Primary Examiner(s): Hunter, Daniel S.
• Application Number:
  US08/719,805
• Time in Patent Office: 937 Days
• Field of Search: 381/106, 381/107, 381/108, 379/347, 379/406, 379/414, 379/400
• US Class Current: 379/347
• CPC Class Codes: H03G 5/22 having semiconductor devices
• CPC Class Codes: H03G 9/005 of digital or coded signals
• CPC Class Codes: H03G 9/025 frequency-dependent volume compression or expansion, e.g. multiple-band systems H03G9/10, H03G9/18 take precedence
• CPC Class Codes: H04M 3/002 Applications of echo suppressors or cancellers in telephonic connections in two-way loud-speaking telephone systems H04M9/08, echo suppressors or cancellers per se H04B3/20
• CPC Class Codes: H04M 3/40 Applications of speech amplifiers

Abstract

A system (130) for providing enhancement to a voice-band signal in a telecommunications network (138) is provided. The present system (130) includes a power averager (18) for determining the average power of the voice-band signal. The present system (130) also includes an equalizer (132) for attenuating a predetermined portion of the voice-band signal and an output scaler (134) for scaling the equalized voice-band signal with a scaling factor. The system (130) of the present invention also includes an automatic gain enhancer (136) for applying an automatic gain factor to the scaled voice-band signal and wherein the automatic gain factor is dependent upon the average power of the input voice-band signal.

Claims

1. A method for providing voice enhancement in a telecommunications network comprising the steps of:

determining an average power of an input voice-band signal;

generating a control signal in response to the average power of the input voice-band signal;

determining an automatic gain factor in response to the average power of the input voice-band signal;

equalizing the input voice-band signal by attenuating a predetermined portion of the input voice-band signal in response to the control signal;

scaling the equalized voice-band signal with a scaling factor in response to the control signal; and

applying the automatic gain factor to the scaled voice-band signal in response to the control signal.

2. The method of claim 1 further comprising the steps of:

detecting voice-band data in the input voice-band signal and responding to the detection of voice-band data in the input signal by;

suspending the equalization of the input voice-band signal, and

setting the scaling factor and automatic gain factor to provide no change to the input voice-band signal.

3. The method of claim 1 wherein the applying the automatic gain factor step further comprises:

providing gain to voice-band signals having an average power above a predetermined minimum average power level but below a first predetermined power level;

providing no change to voice-band signals having an average power above the first predetermined power level and below a second predetermined power level, and wherein the second predetermined power level is greater than the first predetermined power level, and

attenuating voice-band signals having an average power level above the second predetermined power level.

4. The method of claim 1 wherein the determining the average power, determining an automatic gain factor, equalizing, scaling, and applying steps are performed in an echo canceler of a telecommunications network.

5. The method of claim 1 wherein the predetermined portion of the input voice-band signal is above substantially 300 Hz.

6. The method of claim 1 wherein the applying the automatic gain factor step further comprises using the previously determined automatic gain factor for a predetermined period of time.

7. The method of claim 1 wherein the determining an automatic gain factor step further comprises the step of limiting the amount of change between consecutive automatic gain factors.

8. The method of claim 1 further comprising the steps of:

detecting periods of silence in the input voice-band signal, and responding to the detection of silence in the input voice-band signal by;

suspending the equalization of the input voice-band signal, and

setting the scaling factor and automatic gain factor to provide no change to the input voice-band signal.

9. The method of claim 8 further comprising the step of attenuating the input voice-band signal so that the noise level of the periods of silence is minimized.

10. A method for providing enhancement to a voice-band signal in a telecommunications network, comprising the steps of:

determining an average power of an input voice-band signal;

determining an automatic gain factor in response to the average power of the input voice-band signal;

generating a control signal in response to the average power of the input voice-band signal;

equalizing the input voice-band signal by attenuating a predetermined portion of the input voice-band signal in response to the control signal;

scaling the equalized voice-band signal with a scaling factor in response to the control signal; and

applying the automatic gain factor to the scaled voice-band signal in response to the control signal by;

providing gain to voice-band signals having an average power above a predetermined minimum average power level but below a first predetermined power level,

providing no change to voice-band signals having an average power above the first predetermined power level and below a second predetermined power level, and wherein the second predetermined power level is greater than the first predetermined power level, and

attenuating voice-band signals having an average power level above the second predetermined power level.

11. The method of claim 10 wherein the determining the average power, determining an automatic gain factor, equalizing, scaling, and applying steps are performed in an echo canceler of a telecommunications network.

12. The method of claim 10 wherein the predetermined portion of the input voice-band signal is above substantially 300 Hz.

13. The method of claim 10 wherein the applying the automatic gain factor step further comprises using the previously determined automatic gain factor for a predetermined period of time.

14. The method of claim 10 further comprising the steps of:

detecting voice-band data in the input voice-band signal and responding to the detection of voice-band data in the input signal by;

suspending the equalization of the input voice-band signal, and

setting the scaling factor and automatic gain factor to provide no change to the input voice-band signal.

15. The method of claim 10 further comprising the steps of:

detecting periods of silence in the input voice-band signal and responding to the detection of silence in the input voice-band signal by;

suspending the equalization of the input voice-band signal, and

setting the scaling factor and automatic gain factor to provide no change to the input voice-band signal.

16. A system for providing enhancement to a voice-band signal in a telecommunications network comprising:

a power averager for determining an average power of the voice-band signal, the power averager generating a control signal in response to the average power of the voice-band signal;

an equalizer for attenuating a predetermined portion of the voice-band signal in response to the control signal;

an output scaler for scaling the equalized voice-band signal with a scaling factor in response to the control signal; and

an automatic gain enhancer for applying an automatic gain factor to the scaled voice-band signal in response to the control signal, and wherein the automatic gain factor is dependent upon the average power of the voice-band signal.

17. The system of claim 16 further comprising a voice-band data detector for detecting voice-band data in the voice-band signal and for preventing the equalizer, output scaler, and the automatic gain enhancer from changing the voice-band signal.

18. The system of claim 16 wherein the automatic gain enhancer further provides:

gain to voice-band signals having an average power above a predetermined minimum average power level but below a first predetermined power level;

no gain or attenuation to voice-band signals having an average power above the first predetermined power level and below a second predetermined power level, and wherein the second predetermined power level is greater than the first predetermined power level; and

attenuates voice-band signals having an average power level above the second predetermined power level.

19. The system of claim 16 further comprising a voice-band data detector for detecting voice-band data in the voice-band signal and wherein the voice-band data detector is operable to prevent the equalizer, output scaler, and the automatic gain enhancer from changing the voice-band signal.

20. The system of claim 16 wherein said power averager, equalizer, output scaler, and automatic gain enhancer are located in an echo canceler of telecommunications network.

21. The system of claim 16 wherein the predetermined portion of the voice-band signal attenuated by said equalizer is above substantially 300 Hz.

22. The system of claim 16 further comprising a gain/attenuation look-up table for providing the automatic gain factor to be used by said automatic gain enhancer on the voice-band signal.