Stereophonic sound reproduction system for compensating low frequency signal and method thereof

• US 20060239464A1
• Filed: 03/30/2006
• Published: 10/26/2006
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kim, Jeong-Tae, Kang, Tae Ik, Park, Young Cheol, Lee, Jun-Ho, Youn, Dae Hee
• Granted Patent: US 8,085,939 B2
• Time in Patent Office: Days
• US Class Current: 381/1
• CPC Class Codes: H04R 5/04 Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments combinations of amplifiers H03F3/68; stereophonic systems H04S

Abstract

A stereophonic sound reproduction system for compensating a low frequency signal and a method thereof, wherein a mono component signal for compensating low frequency signals which are attenuated when removing a crosstalk of inputted left and right signals inputted is calculated using an average value between the left and right signals, left and right compensation gains which are inversely proportional to an absolute value of a power difference value between the first left and right signals, an amplitude of the calculated mono component signal is controlled according to the left and right compensation gains, and thereafter the mono component signal with the controlled amplitude is added to the left and right signals when removing the crosstalk, whereby the left and right signals from which the crosstalk is removed and to which the mono component signal is added are outputted through left and right speakers to thus prevent distortion of the low frequency signals of original stereophonic sound with maintaining a stereophonic sound effect.

Claims

1. A stereophonic sound reproduction system for compensating a low frequency signal comprising:

a crosstalk removing unit to remove a crosstalk from left and right signals inputted; and

a low frequency signal compensating unit to compensate low frequency signals attenuated when removing the crosstalk by compensating a mono component signal extracted from the left and right signals.

2. The system of claim 1, wherein the mono component signal is generated according to compensation gains which are calculated based upon information related to power difference between the left and right signals.

3. The system of claim 1, wherein the mono component signal is an average value between the left and right signals.

4. The system of claim 1, wherein the crosstalk removing unit includes:

first through fourth compensating filters to compensate the left and right signals using a reverse function of a special transfer function corresponding to each acoustic path;

a first adder to add output signals from the first and third compensating filters to each other to thus remove the crosstalk; and

a second adder to add output signals from the second and fourth compensating filters to each other to thus remove the crosstalk.

5. The system of claim 4, wherein the low frequency signal compensating unit includes:

a low frequency band pass filter to extract the mono component signal by performing a low pass filtering with respect to an average value between the left and right signals;

a first multiplier to multiply the mono component signal by compensation gains calculated using the information related to the power difference between the left and right signals and outputting the multiplied mono component signal to the first adder; and

a second multiplier to multiply the mono component signal by the compensation gains and to thus output the multiplied mono component signal to the second adder.

6. The system of claim 5, wherein the low frequency band pass filter includes delay required for synchronizing the mono component signal with the output signals from the first through fourth compensating filters of the crosstalk removing unit.

7. The system of claim 1, wherein the low frequency signal compensating unit includes:

a mono component signal extracting unit to extract the mono component signal from the left and right signals;

a compensation gain calculating unit to calculate compensation gains using information related to a power difference between the first left and right signals; and

a compensation mono component signal outputting unit to add the mono component signal of which amplitude has been controlled according to the compensation gains respectively to the left and right signals when removing the crosstalk of the left and right signals.

8. The system of claim 7, wherein the mono component signal extracting unit extracts the mono component signal using an equation,

Y=[(L1+R1)/2]*M(z),

wherein (L1+R1)/2 denotes an average value between the first left and right signals (L and R), M(z) denotes a low frequency band pass filter including delay required for synchronizing the (L1+R1)/2 with the output signals from the first through fourth compensating filters of the crosstalk removing unit, * denotes a convolution calculation, and γ

denotes the extracted mono component signal.

9. The system of claim 7, wherein the compensation gain calculating unit calculates the compensation gains using an equation,

$\alpha$

= 1 - 

p L - p R 



p L + p R 

wherein α

denotes the left compensation gain, β

denotes the right compensation gain, P_L denotes the power of the first left signal and P_R denotes the power of the first right signal.

10. The system of claim 9, wherein the power of the left signal is calculated using an equation,

P_L=P_L(n)=γ

·

P_L(n−

1)+(1−

γ

)·

L²(n)

wherein P_L(n−

1) denotes a previously accumulated power value, L²(n−

1) denotes current power of the first left signal L and γ

denotes a weight value for adapting the power P_L to a change in the first left signal L.

11. The system of claim 9, wherein the power of the right signal is calculated using an equation,

P_R=P_R(n)=γ

·

P_R(n−

1)+(1−

γ

)·

R²(n1)

wherein P_R(n−

1) denotes a previously accumulated power value, R²(n−

1) denotes current power of the first right signal R and γ

denotes γ

weight value to adapt the power P_R to a change in the first right signal R.

12. The system of claim 7, wherein the compensation mono component signal generating unit includes:

a first multiplier to multiply the mono component signal by the compensation gains and to output the multiplied mono component signal to a first adder of the crosstalk removing unit; and

a second multiplier to multiply the mono component signal by the compensation gains and to output the multiplied mono component signal to a second adder of the crosstalk removing unit.

13. The system of claim 1, further comprising left and right speakers to receive signals respectively outputted from the crosstalk removing unit.

14. A stereophonic sound reproduction method for compensating low frequency signals comprising:

removing a crosstalk from left and right signals inputted;

generating a mono component signal to compensate a low frequency signal attenuated when removing the crosstalk; and

adding the generated mono component signal to the left and right signals when removing the crosstalk.

15. The method of claim 14, wherein the generating of the mono component signal includes:

extracting the mono component signal from the left and right signals;

calculating left and right compensation gains based upon information related to a power difference between the left and right signals; and

controlling an amplitude of the extracted mono component signal according to the left and right compensation gains.

16. The method of claim 15, wherein the mono component signal is extracted using an equation,

Y=[(L+R)/2]*M(z),

wherein, (L+R)/2 denotes the average value between the first left and right signals L and R, M(z) denotes a low frequency band pass filter including delay required for synchronizing the (L+R)/2 with the second left and right signals L and R from which the crosstalk has been removed, * denotes a convolution calculation, and Y denotes the extracted mono component signal.

17. The method of claim 15, wherein the left and right compensation gains are calculated using an equation,

$\alpha$

= 1 - 

p L - p R 



p L + p R 

$\mathrm{\beta <br><br>}=1-\frac{<br><br>p_R-p_L<br><br>}{<br><br>p_L+p_R<br><br>}$

wherein α

denotes the left compensation gain, β

denotes the right compensation gain, P_L denotes the power of the first left signal and P_R denotes the power of the first right signal.

18. The method of claim 15, wherein the power of the left signal is calculated using an equation,

P_L=P_L(n)=γ

·

P_L(n−

1)+(1−

γ

)·

L²(n)

wherein P_L(n−

1) denotes a previously accumulated power value, L²(n−

1) denotes current power of the first left signal L and γ

denotes a weight value for adapting the power P_L to a change in the first left signal L.

19. The system of claim 17, wherein the power of the right signal is calculated using an equation,

P_R=P_R(n)=γ

·

P_R(n−

1)+(1−

γ

)·

R²(n)

wherein P_R(n−

1) denotes a previously accumulated power value, R²(n−

1) denotes current power of the first right signal R and γ

denotes a weight value to adapt the power P_R to a change in the first right signal R.