Electronic device, echo signal cancelling method thereof and non-transitory computer readable recording medium

1. An electronic device comprising:

a speaker configured to output a sound corresponding to a reference signal;

a microphone configured to obtain a microphone signal by obtaining a received sound; and

a filter configured to cancel an echo signal of the reference signal from the microphone signal,

wherein the filter comprises:

a first filter configured to estimate the echo signal of the reference signal and to cancel the estimated echo signal from the microphone signal, and

a second filter configured to obtain an adaptive gain to cancel a residual echo from the microphone signal in which the estimated echo signal is canceled, and obtain an output signal based on the obtained adaptive gain and the microphone signal in which the estimated echo signal is canceled,

wherein the filter is further configured to:

divide each of the microphone signal and the reference signal into a magnitude and a phase respectively,

obtain the output signal based on the magnitude of the microphone signal and the magnitude of the reference signal.

2. The electronic device as claimed in claim 1 , wherein the filter is further configured to convert the microphone signal and the reference signal into a frequency domain, obtain the output signal by using the microphone signal and the reference signal, convert the obtained output signal into a time domain, and output the converted signal.

3. The electronic device as claimed in claim 2 , wherein the filter is further configured to multiply a magnitude of the obtained output signal by the phase of the microphone signal.

4. The electronic device as claimed in claim 1 , wherein the second filter is further configured to estimate a dispersion value of the residual echo and obtain an adaptive gain by using the estimated dispersion value and the microphone signal in which the estimated echo signal is canceled.

5. The electronic device as claimed in claim 4 , wherein the dispersion value of the residual echo, λ d , is estimated by

λ d ( l,k )=α 2 ( l,k )λ d ( l− 1, k )+(1−α 2 ( l,k ))·| c ( l,k ) X 2 ( l,k )− F 2 ( l,k )|

wherein α(l,k) is a decaying coefficient of an adaptive filter coefficient H(l,k), c(l,k) is a coupling coefficient between a reference signal and a microphone signal, X(l,k) is a reference signal, F(l,k) is an estimated echo signal of a reference signal, 1 is a frame index, and k is a frequency component index.

6. The electronic device as claimed in claim 1 , wherein the second filter is configured to obtain an adaptive gain by using one or more frequency components of the microphone signal in which the estimated echo signal is canceled.

7. The electronic device as claimed in claim 1 , wherein the first filter comprises a plurality of adaptive filters configured to operate in different frequency bands.

8. The electronic device as claimed in claim 1 , further comprising:

a communicator configured to transmit the obtained output signal to an external device.

9. The electronic device as claimed in claim 1 , further comprising:

a voice recognizer configured to perform a voice recognition by using the obtained output signal and to obtain a control signal according to a result of the voice recognition.

10. An echo signal cancelling method of an electronic device comprising:

obtaining a microphone signal by obtaining a sound received by the electronic device;

estimating an echo signal of a reference signal which is output from the electronic device;

cancelling the estimated echo signal from the microphone signal;

obtaining an adaptive gain to cancel a residual echo from the microphone signal in which the estimated echo signal is canceled; and

obtaining an output signal based on the obtained adaptive gain and the microphone signal in which the estimated echo signal is canceled,

wherein the obtaining the output signal comprises dividing each of the microphone signal and the reference signal into a magnitude and a phase respectively, and obtaining the output signal of the reference based on the magnitude of the microphone signal and the magnitude of the reference signal.

11. The echo signal cancelling method as claimed in claim 10 , wherein the obtaining the adaptive gain comprises estimating a dispersion value of the residual echo and obtaining an adaptive gain by using the estimated dispersion value and an error signal.

12. The echo signal cancelling method as claimed in claim 11 , wherein the dispersion value of the residual echo,λ d , is estimated by

λ d ( l,k )=α 2 ( l,k )λ d ( l− 1, k )+(1−α 2 ( l,k ))·| c ( l,k ) X 2 ( l,k )− F 2 ( l,k )|

wherein α(l,k) is a decaying coefficient of an adaptive filter coefficient H(l,k), c(l,k) is a coupling coefficient between a reference signal and a microphone signal, X(l,k) is a reference signal, F(l,k) is an estimated echo signal of a reference signal, 1 is a frame index, and k is a frequency component index.

13. The echo signal cancelling method as claimed in claim 10 , wherein the obtaining the adaptive gain comprises obtaining an adaptive gain by using one or more frequency components of the microphone signal in which the estimated echo signal is canceled.

14. The echo signal cancelling method as claimed in claim 10 , further comprising:

converting the microphone signal and the reference signal into a frequency domain; and

dividing each of the microphone signal and the reference signal into a magnitude and a phase,

wherein the cancelling the echo signal, the obtaining the adaptive gain, and the obtaining the output signal use the magnitude of the divided microphone signal and the magnitude of the divided reference signal, and

wherein the obtaining the output signal further comprises multiplying the obtained output signal by the phase of the microphone signal, converting the obtained output signal into a time domain, and outputting the converted signal.

15. The echo signal cancelling method as claimed in claim 10 , wherein the cancelling the estimated echo signal comprises estimating an echo signal by using a plurality of adaptive filters which operate in different frequency bands.

16. The echo signal cancelling method as claimed in claim 10 , further comprising:

transmitting the obtained output signal to an external device.

17. The echo signal cancelling method as claimed in claim 10 , further comprising:

performing a voice recognition by using the obtained output signal, and

obtaining a control signal according to a result of the voice recognition.

18. A non-transitory computer readable recording medium comprising a program to execute an echo signal cancelling method of an electronic device, the method comprising:

obtaining a microphone signal by obtaining a sound received by the electronic device;

estimating an echo signal of a reference signal which is output from the electronic device;

cancelling the estimated echo signal from the microphone signal;

obtaining an adaptive gain to cancel a residual echo from the microphone signal in which the estimated echo signal is canceled; and

obtaining an output signal based on the obtained adaptive gain and the microphone signal in which the estimated echo signal is canceled,

wherein the obtaining the output signal comprises dividing each of the microphone signal and the reference signal into a magnitude and a phase respectively, and obtaining the output signal of the reference based on the magnitude of the microphone signal and the magnitude of the reference signal.