Audio signal processing method, audio apparatus therefor, and electronic apparatus therefor

An audio apparatus including a decorrelator for generating decorrelated signals by applying a phase shifting value adjusted based on a correlation difference between audio signals included in a multi-channel signal to the audio signals; and a speaker set including at least two speakers for outputting acoustic signals corresponding to the decorrelated signals.

BACKGROUND

Exemplary embodiments relate to an audio signal processing method, an audio apparatus using the same, and an electronic apparatus using the same, and more particularly, to an audio signal processing method for receiving a multi-channel signal and outputting corresponding acoustic signals, an audio apparatus using the same, and an electronic apparatus using the same.

2. Description of the Related Art

Audio apparatuses may output received multi-channel signals through a plurality of speakers. In addition, the audio apparatuses may receive a voice signal corresponding to a voice of a user, recognize the received voice signal, and perform an operation corresponding to a command, operation, or request based on the recognized voice signal. Hereinafter, the recognizing of a received voice signal and the performing of an operation corresponding to a command, operation, or request based on the recognized voice signal are called a voice recognition operation.

In an audio apparatus capable of performing the voice recognition operation, when a voice signal is received through a predetermined microphone while acoustic signals are being output through a plurality of speakers, the audio apparatus must acquire only the voice signal by removing the acoustic signals from among signals input to the microphone. Then, the audio apparatus recognizes the acquired voice signal.

To remove acoustic signals as described above, Multi-Channel Acoustic Echo Cancellation (MCAEC) is used. MCAEC may be implemented using an echo cancellation filter.

If the acoustic signals output through the plurality of speakers have a low correlation, the echo cancellation filter converges to a predetermined value, thereby effectively canceling the acoustic signals. However, if the acoustic signals output through the plurality of speakers have a high correlation, the echo cancellation filter diverges without converging. Accordingly, since residual echo remains in a signal for voice recognition, the voice recognition operation cannot be effectively performed.

That is, if the echo cancellation filter cannot effectively cancel the acoustic signals, the audio apparatus cannot correctly recognize the voice signal and cannot perform an operation or command corresponding to the voice signal.

Thus, in audio apparatuses capable of recognizing a voice signal, an audio apparatus for effectively lowering a correlation between acoustic signals output to a plurality of speakers is necessary.

SUMMARY

The exemplary embodiments provide an audio signal processing method for effectively lowering a correlation between acoustic signals output to a plurality of speakers, an audio apparatus therefor, and an electronic apparatus therefor.

The exemplary embodiments also provide an audio signal processing method for correctly recognizing an input voice signal and an electronic apparatus therefor.

According to an aspect of an exemplary embodiment, an audio apparatus includes: a decorrelator for generating decorrelated signals by applying a phase shifting value adjusted based on a correlation difference between audio signals included in a multi-channel signal to the audio signals; and a speaker set including at least two speakers for outputting acoustic signals corresponding to the decorrelated signals.

The decorrelator may generate the decorrelated signals by applying a phase shifting value adjusted based on a phase difference between the audio signals to the audio signals.

The decorrelator may receive the multi-channel signal including first and second channel audio signals.

The decorrelator may reduce the phase shifting value when a phase difference between the first and second channel audio signals is great.

The decorrelator may set the phase shifting value to 0 when the phase difference between the first and second channel audio signals is 180°.

The decorrelator may set the phase shifting value to a predetermined limit value when the phase difference between the first and second channel audio signals is 0°.

The decorrelator may generate first and second decorrelated signals corresponding to the first and second channel audio signals by subtracting the phase shifting value from a phase of the first channel audio signal and adding the phase shifting value to a phase of the second channel audio signal, respectively.

The decorrelator may include: a pre-processor for receiving the multi-channel signal, including the first and second channel audio signals, dividing the multi-channel signal into a plurality of sub-bands, and generating first and second channel sub-audio signals in each of the plurality of sub-bands; a decorrelation processor for generating first and second sub-decorrelated signals by applying a phase shifting value adjusted based on a phase difference between the first and second channel sub-audio signals to the first and second channel sub-audio signals; and a synthesizer for generating the first decorrelated signal by synthesizing the first sub-decorrelated signals in the plurality of sub-bands and generating the second decorrelated signal by synthesizing the second sub-decorrelated signals in the plurality of sub-bands.

The decorrelation processor may generate the first and second sub-decorrelated signals by setting a corrected phase shifting value by multiplying the phase shifting value by a predetermined weighting value based on sub-bands, subtracting the corrected phase shifting value from a phase of the first channel sub-audio signal, and adding the corrected phase shifting value to a phase of the second channel sub-audio signal.

The decorrelation processor may set the predetermined weighting value based on sub-bands.

The decorrelation processor may set the predetermined weighting value in one sub-band and the predetermined weighting value in another sub-band adjacent to the one sub-band to have different signs.

The decorrelation processor may divide the plurality of sub-bands into a plurality of groups and set the predetermined weighting value based on groups.

The decorrelation processor may set the predetermined weighting value in one group and the predetermined weighting value in another group adjacent to the one group to have different signs.

The audio apparatus may further include: an echo filter unit for generating echo signals corresponding to the decorrelated signals; a microphone for receiving the acoustic signals and a voice signal; and a processor for processing voice recognition on a subtraction signal obtained by subtracting the echo signals from an output signal of the microphone.

According to another aspect of an exemplary embodiment, an electronic apparatus includes: a decorrelator for generating decorrelated signals by applying a phase shifting value adjusted based on a correlation difference between audio signals included in a multi-channel signal to the audio signals; an echo filter unit for generating echo signals corresponding to the decorrelated signals; a speaker set including at least two speakers for outputting acoustic signals corresponding to the decorrelated signals; a microphone for receiving the acoustic signals and a voice signal; and a processor for processing voice recognition on a subtraction signal obtained by subtracting the echo signals from an output signal of the microphone.

According to another aspect of an exemplary embodiment, an audio signal processing method includes: receiving a multi-channel signal including audio signals; adjusting a phase shifting value based on a correlation difference between the audio signals; and generating decorrelated signals by applying the phase shifting value to the audio signals.

DETAILED DESCRIPTION

An audio signal processing method, an audio apparatus, and an electronic apparatus will now be described in detail with reference to the accompanying drawings.

FIG. 1is a perspective view of an electronic apparatus100. The electronic apparatus100shown inFIG. 1is, for example, a digital TV. The electronic apparatus100may be any one of various electronic products, including an audio apparatus for outputting an audio signal. For example, the electronic apparatus100may be a digital TV, an audio system, a refrigerator, a washing machine, a personal computer, a mobile computer, a pad-type terminal, or a mobile phone.

The electronic apparatus100includes an audio apparatus (not shown) including a decorrelator (not shown) and a speaker set. The decorrelator may be included in a circuit block included in the electronic apparatus100, and the speaker set may include at least two speakers, for example, first and second speakers110and120.

The electronic apparatus100may further include at least one of a microphone130and a display unit140. The microphone130may include a microphone array (not shown) and may receive all audible audio signals. In detail, the microphone130may receive a voice signal generated by a user.

The decorrelator adjusts and outputs a correlation among a plurality of audio signals included in a multi-channel signal. The correlation-adjusted audio signals are output through the first and second speakers110and120.

When the user inputs a voice signal into the microphone130while audio signals are being output from the first and second speakers110and120, the microphone130receives the voice signal in addition to the audio signals output from the first and second speakers110and120.

For example, assuming that the electronic apparatus100is a digital TV capable of performing a video call function, the digital TV may output a Picture-In-Picture (PIP) screen on the display unit140. In a PIP mode, the display unit140may output broadcasting images on a main screen and output images of a video call on a sub-screen.

As another example, assuming that the electronic apparatus100is a digital TV capable of performing a voice recognition control, when the user inputs a predetermined command or request into the digital TV with a voice signal, the digital TV may perform an operation corresponding to the input voice signal. That is, when the user inputs a voice signal into the microphone130, the electronic apparatus100may perform an operation corresponding to the input voice signal.

When a voice signal is received while audio signals are being output from the first and second speakers110and120, the electronic apparatus100must detect or discern only the voice signal and not the audio signals output from the first and second speakers110and120. To extract the voice signal from among all signals input to the microphone130, audio signals output from the speakers must be cancelled from among all the signals input to the microphone130by using an echo cancellation filter (not shown).

The audio signals output from the first and second speakers110and120are input to the microphone130through various paths111,112,113,121,122, and123according to a surrounding environment where the electronic apparatus100is located. Hereinafter, paths111,112,113,121,122, and123are called ‘actual echo paths’. The actual echo paths may vary according to the surrounding environment and noise when the audio signals are output, so it is difficult to clearly determine the actual echo paths. Thus, an impulse response function is designed by estimating echo paths corresponding to the actual echo paths (hereinafter, ‘estimated echo paths’) and reflecting the estimated echo paths. The echo cancellation filter may filter echo signals corresponding to the audio signals based on the designed impulse response function. The echo cancellation filter may be implemented using an echo filter unit620and an adder671, which will be described with reference toFIG. 6.

The electronic apparatus100may receive the multi-channel signal including a right channel (R-channel) audio signal and a left channel (L-channel) audio signal from the outside or may itself generate the multi-channel signal. When the speaker set includes the first and second speakers110and120, the first speaker110may output the R-channel audio signal, and the second speaker120may output the L-channel audio signal.

Electronic apparatuses and audio apparatuses which may be included in the electronic apparatuses will now be described in detail with reference toFIGS. 2 to 7.

FIG. 2is a block diagram of an audio apparatus200according to an aspect of an exemplary embodiment.

Referring toFIG. 2, the audio apparatus200includes a decorrelator210and a speaker set250.

The decorrelator210generates decorrelated signals Sout corresponding to audio signals included in a multi-channel signal Sm by reducing a correlation between the audio signals

In detail, the decorrelator210receives the multi-channel signal Sm and generates the decorrelated signals Sout by applying a phase shifting value adjusted based on a correlation difference between the audio signals included in the multi-channel signal Sm to the audio signals. The multi-channel signal Sm includes a plurality of audio signals corresponding to a plurality of channels. For example, the multi-channel signal Sm may include an R-channel audio signal and an L-channel audio signal. As another example, the multi-channel signal Sm may include 5.1-channel audio signals, 7.1-channel audio signals, or 10.2-channel audio signals.

The speaker set250includes at least two speakers for outputting acoustic signals corresponding to the decorrelated signals Sout generated by the decorrelator210. The number of speakers included in the speaker set250may vary according to the number of audio signals included in the multi-channel signal Sm.

In detail, the decorrelator210generates the decorrelated signals Sout by applying to the audio signals a phase shifting value adjusted based on a phase difference between the audio signals included in the multi-channel signal Sm. The phase shifting value is a value to be subtracted from or added to a phase of an audio signal included in the multi-channel signal Sm. A corrected phase shifting value may be set by multiplying the phase shifting value by a predetermined weighting value. The corrected phase shifting value will be described in detail with reference toFIG. 5below. The phase shifting value may be a positive (+) value from 0 to a predetermined limit value. The predetermined limit value is a phase shifting value applied when a phase difference between audio signals is 0 or a value close to 0 and may be differently set according to a filtering performance, a target voice recognition ratio, and a product specification of an echo cancellation filter (not shown) included in the audio apparatus200.

In addition, the decorrelator210may receive the multi-channel signal Sm, including first and second channel audio signals, from an external broadcasting station. The first and second channel audio signals may correspond to the R-channel audio signal and the L-channel audio signal, respectively. Hereinafter, the multi-channel signal Sm, including the first and second channel audio signals, is illustrated. In addition, it is illustrated that the decorrelator210generates first and second decorrelated signals corresponding to the first and second channel audio signals, respectively.

For example, when the multi-channel signal Sm, including the R-channel audio signal and the L-channel audio signal, is received, the decorrelator210sets a phase shifting value based on a phase difference between the R-channel audio signal and the L-channel audio signal. Then, the decorrelator210may generate an R-channel decorrelated signal and an L-channel decorrelated signal corresponding to the R-channel audio signal and the L-channel audio signal, respectively, so that the R-channel decorrelated signal and the L-channel decorrelated signal have phases obtained by adding the phase shifting value to a phase of the R-channel audio signal and subtracting the phase shifting value from a phase of the L-channel audio signal, respectively.

In detail, the decorrelator210reduces the phase shifting value in inverse proportion to a phase difference between the R-channel audio signal and the L-channel audio signal.

In addition, the decorrelator210may set the phase shifting value to 0 when the phase difference between the first and second channel audio signals is 180°. If the phase difference between the first and second channel audio signals is 180°, i.e., π (pi), the first and second channel audio signals have opposite phases to each other. Thus, the phase shifting value is set to 0 so that the first and second decorrelated signals have a low correlation even though the first and second decorrelated signals are generated.

In addition, the decorrelator210may set the phase shifting value to a predetermined limit value when the phase difference between the first and second channel audio signals is 0°.

In addition, the decorrelator210may set phase values for the first and second decorrelated signals by subtracting the phase shifting value from a phase of the first channel audio signal and adding the phase shifting value to a phase of the second channel audio signal. Then, the decorrelator210may generate the first and second decorrelated signals having the phase values for the first and second decorrelated signals.

In addition, the decorrelator210may set phase values for the first and second decorrelated signals by subtracting a corrected phase shifting value from the phase of the first channel audio signal and adding the corrected phase shifting value to the phase of the second channel audio signal.

FIG. 3is a block diagram of an audio apparatus300according to an aspect of exemplary embodiment. Referring toFIG. 3, the audio apparatus300may include a decorrelator310and a speaker set350. Since the audio apparatus300, the decorrelator310, and the speaker set350correspond to the audio apparatus200, the decorrelator210, and the speaker set250, respectively, a repeated description thereof is omitted. Hereinafter, an operation of generating decorrelated signals by lowering a correlation between audio signals is called a decorrelation operation.

The decorrelator310may divide audio signals included in a multi-channel signal Sm into a plurality of sub-bands and generate decorrelated signals based on sub-bands. A sub-band indicates a frequency band from when a frequency band of the multi-channel signal Sm is divided into a plurality of sub-frequency bands. Hereinafter, it is illustrated that the multi-channel signal Sm includes first and second channel audio signals. As described above, the first and second channel audio signals may correspond to an R-channel audio signal and an L-channel audio signal, respectively.

FIG. 3illustrates that the decorrelator310divides the audio signals included in the multi-channel signal Sm into n sub-bands and performs a decorrelation operation for generating decorrelated signals for the n sub-bands.

In detail, the decorrelator310includes a pre-processor320, a decorrelation processor330, and a synthesizer340.

The pre-processor320receives the multi-channel signal Sm, including the first and second channel audio signals, and divides the multi-channel signal Sm into first to nth sub-audio signals S_sub1to S_subn.

That is, the pre-processor320divides the multi-channel signal Sm into n frequency bands and outputs the first sub-audio signal S_sub1of a first sub-band to the nth sub-audio signal S_subn of an nth sub-band. The multi-channel signal Sm may include the first and second channel audio signals. In addition, the first sub-audio signal S_sub1of the first sub-band may include first and second channel sub-audio signals of the first sub-band, and the nth sub-audio signal S_subn of the nth sub-band may include first and second channel sub-audio signals of the nth sub-band.

The decorrelation processor330generates first and second sub-decorrelated signals by applying a phase shifting value in a predetermined sub-band, which is adjusted based on a phase difference between first and second channel sub-audio signals in the predetermined sub-band, to the first and second channel sub-audio signals. The phase shifting value will be described in detail with reference toFIG. 4below.

FIG. 4illustrates graphs410,420, and430for describing the phase shifting value adjustment performed by the audio apparatus200or300according to one or more aspects of exemplary embodiments. InFIG. 4, an X-axis indicates a phase difference between first and second channel audio signals, and a Y-axis indicates a phase shifting value. In addition, the X-axis may indicate a phase difference between first and second channel sub-audio signals in a predetermined sub-band. Hereinafter, the X-axis indicates a phase difference between first and second channel audio signals.

Referring toFIG. 4, the graph410shows a phase shifting value applied in a high frequency band, the graph420shows a phase shifting value applied in an intermediate frequency band, and the graph430shows a phase shifting value applied in a low frequency band.FIG. 4illustrates that a total frequency band is divided into 3 frequency bands, i.e., the high frequency band, the intermediate frequency band, and the low frequency band, and a phase shifting value is adjusted for each divided frequency band. However, it may be designed where the total frequency band is divided into a various number of frequency bands and phase shifting value graphs are optimized for the divided frequency bands. In addition, the phase shifting value graphs may be experimentally optimized so that sound quality distortion is minimized while an echo cancellation filter (not shown) does not diverge.

Referring to the graph410ofFIG. 4, when a phase difference between first and second channel audio signals corresponding to the high frequency band is 0°, a phase shifting value is set to a predetermined limit value a, which is the maximum value. In addition, when the phase difference between the first and second channel audio signals is 180°, i.e., π (pi), the phase shifting value may be set to 0 or a value close to 0. In detail, the phase shifting value increases as the phase difference between the first and second channel audio signals is small, and the phase shifting value decreases as the phase difference between the first and second channel audio signals is large.

In addition, as a frequency band goes from the high frequency band to the low frequency band, the frequency band is close to an audible frequency band which a user can recognize well. Since distortion of the first or second channel audio signal increases when a phase shifting value is set large in the low frequency band, which is the audible frequency band, the phase shifting value may be set small in the low frequency band, which is the audible frequency band. On the contrary, since the high frequency band is a frequency band which the user cannot audibly recognize well, the user cannot recognize sound quality distortion well even though the phase shifting value is set large. Thus, the phase shifting value may be set large in the high frequency band. Accordingly, predetermined limit values a, b, and c may be set differently according to frequency bands.

The predetermined limit values a, b, and c of a phase shifting value and forms of the phase shifting value graphs410,420, and430shown inFIG. 4may be experimentally optimized and determined. For example, a phase shifting value may be set through sound quality distortion experiments so that the echo cancellation filter does not diverge while the sound quality distortion is minimized.

The decorrelation processor330may include first to nth sub-processors331,332, and333for performing the decorrelation operation for n sub-frequency bands.

In detail, the first sub-processor331receives first and second channel sub-audio signals S_sub1in a first sub-band and generates first and second channel sub-decorrelated signals S_su11and S_su12corresponding to the first and second channel sub-audio signals S_sub1. The second sub-processor332receives first and second channel sub-audio signals S_sub2in a second sub-band and generates first and second channel sub-decorrelated signals S_su21and S_su22corresponding to the first and second channel sub-audio signals S_sub2. The nth sub-processor333receives first and second channel sub-audio signals S_subn in an nth sub-band and generates first and second channel sub-decorrelated signals S_sun1and S_sun2corresponding to the first and second channel sub-audio signals S_subn.

For example, when the correlation operation in the second sub-band is used as an example, the decorrelation processor330receives the sub-audio signal S_sub2in the second sub-band, which includes the first and second channel sub-audio signals. The second sub-processor332adjusts a phase shifting value based on a phase difference between the first and second channel sub-audio signals. The second sub-processor332generates the first channel sub-decorrelated signal S_su21by applying the phase shifting value to the first channel sub-audio signal of the second sub-band and generates the second channel sub-decorrelated signal S_su22by applying the phase shifting value to the second channel sub-audio signal of the second sub-band.

Since operations of the first sub-processor331to the nth sub-processor333are the same as the operation of the second sub-processor332described above, a detailed description thereof is omitted.

In detail, the synthesizer340generates the first decorrelated signal Sc1corresponding to the total frequency band by synthesizing the first channel sub-decorrelated signals S_su11, S_su21, . . . , S_sun1in the n sub-bands.

In addition, the synthesizer340generates the second decorrelated signal Sc2corresponding to the total frequency band by synthesizing the second channel sub-decorrelated signals S_su12, S_su22, . . . , S_sun2in the n sub-bands.

The decorrelation operation of the decorrelator310allows the first decorrelated signal Sc1and the second decorrelated signal Sc2generated by the synthesizer340to have a low correlation therebetween.

The speaker set350may include a plurality of speakers, namely, first and second speakers351and352, for receiving the plurality of decorrelated signals, namely, the first and second decorrelated signals Sc1and Sc2, output from the decorrelator310and outputting output audio signals, namely, first and second audio signals Sout1and Sout2, corresponding to the decorrelated signals, namely, the first and second decorrelated signals Sc1and Sc2, respectively.FIG. 3illustrates that the speaker set350includes the first speaker351and the second speaker352.

In detail, the first speaker351converts the first decorrelated signal Sc1to a first audio signal Sout1which the user can audibly recognize and outputs the first audio signal Sout1. The second speaker352converts the second decorrelated signal Sc2to a second audio signal Sout2which the user can audibly recognize and outputs the second audio signal Sout2.

In addition, the decorrelation processor330may set a corrected phase shifting value by multiplying a phase shifting value by a predetermined weighting value. Then, the decorrelation processor330may generate first and second sub-decorrelated signals by subtracting the corrected phase shifting value from the phase of the first channel sub-audio signal and adding the corrected phase shifting value to the phase of the second channel sub-audio signal, respectively. The predetermined weighting value may be set differently based on sub-bands. The predetermined weighting value may be set by the decorrelation processor330or may be received from the outside as an experimentally optimized value.

In addition, as a frequency band goes from a sub-band of the low frequency band to a sub-band of the high frequency band, the predetermined weighting value may be increased.

FIGS. 5A and 5Billustrate other graphs for describing a phase shifting value adjustment performed by the audio apparatus200or300according to one or more aspects of exemplary embodiments.FIG. 5Ais a graph for describing a predetermined weighting value according to an aspect of an exemplary embodiment, andFIG. 5Bis a graph for describing a predetermined weighting value according to another aspect of an exemplary embodiment.

Referring toFIGS. 5A and 5B, an X-axis indicates the order of sub-bands, and a Y-axis indicates a predetermined weighting value. In detail, the X-axis indicates the order k of sub-bands in the low frequency band to the high frequency band when the total frequency band of the multi-channel signal Sm is divided into n sub-bands.

Referring toFIG. 5A, k=1 indicates the first sub-band, and the first sub-processor331generates first and second sub-decorrelated signals corresponding to the first and second channel sub-audio signals by using a corrected phase shifting value by multiplying a phase shifting value by a weighting value w1corresponding to the first sub-band. A weighting value w2is a weighting value applied in the second sub-band, and a weighting value w3is a weighting value applied in the nth sub-band.

In detail, a predetermined weighting value in one sub-band (e.g., k=1) and a predetermined weighting value in another sub-band (e.g., k=2) adjacent to the one sub-band may be set to have different signs. For example, a positive weighting value may be set in sub-bands of an odd order, and a negative weighting value may be set in sub-bands of an even order.

In addition, an absolute value of a weighting value may be set to increase as an order value of a sub-band increases. For example, as a value of the order k of a sub-band increases, an absolute value of a weighting value increases as w1, w2, and w3.

Referring toFIGS. 3 and 5A, when the order k of a sub-band is 1, the first sub-audio signal S_sub1of the first sub-band, which includes the first channel sub-audio signal and the second channel sub-audio signal, is input to the first sub-processor331. A phase of the first channel sub-audio signal may be represented as ejφ1(k), and the second channel sub-audio signal may be represented as ejφ2(k). Here, k denotes an order of a sub-band, φ1(k) denotes a phase value of the first channel sub-audio signal in a kth sub-band, and φ2(k) denotes a phase value of the second channel sub-audio signal in the kth sub-band.

The phase shifting value described inFIG. 4may be represented as ejφΔ(k). When k=1, the first sub-processor331may set a phase of a first channel sub-decorrelated signal in the kth sub-band as ej(φ1−φΔ)(k)by subtracting the phase shifting value from the phase of the first channel sub-audio signal. In addition, the first sub-processor331may set a phase of a second channel sub-decorrelated signal in the kth sub-band as ej(φ2+φΔ)(k)by adding the phase shifting value to the phase of the second channel sub-audio signal.

When first and second channel sub-decorrelated signals are generated by applying a corrected phase shifting value, a weighting value applied in a predetermined sub-band k may be represented as wk. In this case, the corrected phase shifting value may be represented as wk·φΔ. Accordingly, when k=1, the first sub-processor331may set the phase of the first channel sub-decorrelated signal in the kth sub-band as by ej(φ1−wk·φΔ)(k)subtracting the corrected phase shifting value from the phase of the first channel sub-audio signal. In addition, the first sub-processor331may set the phase of the second channel sub-decorrelated signal in the kth sub-band as ej(φ2+wk·φΔ)(k)by adding the corrected phase shifting value to the phase of the second channel sub-audio signal.

In addition, the first channel sub-decorrelated signal is generated by synthesizing first channel sub-decorrelated signals of all sub-bands, and the second channel sub-decorrelated signal is generated by synthesizing second channel sub-decorrelated signals of all sub-bands. A magnitude of the first and second channel sub-decorrelated signals may vary according to a magnitude of the first and second channel audio signals, and a product specification, such as a maximum power or amplification efficiency, of the audio apparatus300.

Referring toFIG. 5B, the decorrelator310may divide the plurality of sub-bands into a plurality of groups and set a predetermined weighting value having a different value based on groups. In addition, the decorrelator310may divide the plurality of sub-bands into a plurality of groups and receive a predetermined weighting value having a different value based on groups from the outside.

As shown inFIG. 5B, first to third sub-bands may be set as a first group, group1, fourth to sixth sub-bands may be set as a second group, group2, seventh and eighth sub-bands may be set as a third group, group3, and ninth and greater sub-bands may be set as a fourth group, group4. In addition, one group (e.g., group1) and another group (e.g., group2) adjacent to the one group may be set to have different signs.

When a sub-decorrelated signal is generated by adjusting a phase of a sub-audio signal, if a first sub-decorrelated signal is generated by subtracting a phase shifting value from a phase of a first channel sub-audio signal and a second sub-decorrelated signal is generated by adding the phase shifting value to a phase of a second channel sub-audio signal, spatial perception of sound is biased to one side. Thus, as described with reference toFIGS. 5A and 5B, signs of weighting values in sub-bands may be set differently so that the spatial perception of sound is alternately biased to the left and the right. Accordingly, spatial perception which the user feels when the user listens to audio may be prevented from being biased to one side.

FIG. 6is a block diagram of an electronic apparatus600according to an exemplary embodiment. Referring toFIG. 6, the electronic apparatus600may correspond to the audio apparatus200or300described with reference toFIGS. 2 to 5B. The electronic apparatus600may be an audio apparatus and may further include an echo filter unit620, a microphone640, and a processor670, in comparison with the audio apparatus200or300. A decorrelator610and a speaker set650of the electronic apparatus600correspond to the decorrelator210or310and the speaker set250or350ofFIG. 2or3, respectively. Thus, a repeated description thereof is omitted.

The electronic apparatus600includes the decorrelator610, the echo filter unit620, the microphone640, the speaker set650, and the processor670.

The decorrelator610receives a multi-channel signal Sm including audio signals and outputs decorrelated signals by applying a phase shifting value adjusted based on a correlation difference between the audio signals to the audio signals.

The echo filter unit620generates echo signals corresponding to the decorrelated signals output from the decorrelator610.

The speaker set650outputs acoustic signals corresponding to the decorrelated signals. For example, the decorrelated signals are a first channel decorrelated signal and a second channel decorrelated signal as described above. Hereinafter, an acoustic signal corresponding to the first channel decorrelated signal is called an R-channel audio signal, and an acoustic signal corresponding to the second channel decorrelated signal is called an L-channel audio signal.

The microphone640receives a voice signal Sin and the acoustic signals output from the speaker set650.

The voice signal Sin may be a signal due to talking by the user to control an operation of the electronic apparatus600by voice recognition. Alternatively, the voice signal Sin may be a signal due to talking by the user to input the signal into the electronic apparatus600. The L-channel audio signal may be output through the paths121,122, and123ofFIG. 1, and the R-channel audio signal may be output through the paths111,112, and113ofFIG. 1. The microphone640may receive the L-channel audio signal transmitted through the paths121,122, and123and receive the R-channel audio signal transmitted through the paths111,112, and113. That is, the microphone640may receive the voice signal Sin, the L-channel audio signal, and the R-channel audio signal.

In detail, the echo filter unit620estimates the acoustic signals output from the speaker set650and input to the microphone640, which may vary according to a surrounding environment where the electronic apparatus600is located. The paths of the acoustic signals input to the microphone640may be actual acoustic echo paths and vary according to a surrounding environment, and it is difficult to clearly determine the actual acoustic echo paths. Thus, the echo filter unit620may estimate echo paths corresponding to the actual acoustic echo paths and generate estimated acoustic signals based on the estimated echo paths. The estimated acoustic signals correspond to the actual acoustic signals output from the speaker set650.

The processor670performs voice recognition processing on a subtraction signal obtained by subtracting the echo signals from an output signal of the microphone640. In detail, the processor670may include a controller673and the adder671.

The adder671generates the subtraction signal by subtracting the echo signals output from the echo filter unit620from the output signal of the microphone640.

The controller673performs voice recognition processing on the subtraction signal output from the adder671. In detail, the controller673recognizes voice corresponding to the subtraction signal and performs an operation corresponding to the recognized voice.

For example, the echo filter unit620may generate a first estimated acoustic signal by estimating an acoustic signal output from a first speaker (not shown) included in the speaker set650and generate a second estimated acoustic signal by estimating an acoustic signal output from a second speaker (not shown) included in the speaker set650. The adder671subtracts the first and second estimated acoustic signals output from the echo filter unit620from the output signal of the microphone640. Then, the controller673may perform voice recognition processing on an output signal of the adder671and recognize a command or data according to the output signal of the adder671.

In addition, the above-described echo cancellation filter (not shown) may consist of the echo filter unit620and the adder671.

FIG. 7is a block diagram of an electronic apparatus700according to an exemplary embodiment.

Referring toFIG. 7, the electronic apparatus700corresponds to the electronic apparatus600ofFIG. 6. In the electronic apparatus700ofFIG. 7, which is compared with the device600ofFIG. 6, a multi-channel signal Sm input to a decorrelator710includes first and second channel audio signals, a speaker set750includes a first speaker751for outputting the first channel audio signal and a second speaker752for outputting the second channel audio signal, and an echo filter unit720includes a first filter unit721and a second filter unit722. In addition, a processor770may include a controller773and two adders771and772.

The decorrelator710outputs a first channel decorrelated signal Sc1corresponding to the first channel audio signal and a second channel decorrelated signal Sc2corresponding to the second channel audio signal.

The first speaker751receives the first channel decorrelated signal Sc1and outputs an R-channel audio signal Sout1, which is an acoustic signal which a user can audibly recognize. The second speaker752receives the second channel decorrelated signal Sc2and outputs an L-channel audio signal Sout2, which is an acoustic signal which the user can audibly recognize.

A microphone740receives a voice signal Sin, the R-channel audio signal Sout1, and the L-channel audio signal Sout2and outputs the voice signal Sin, the R-channel audio signal Sout1, and the L-channel audio signal Sout2.

The first filter unit721receives the first channel decorrelated signal Sc1and estimates echo paths through which the R-channel audio signal Sout1is output. Then, the first filter unit721generates a first estimated acoustic signal Sp1corresponding to the first channel decorrelated signal Sc1by applying the first channel decorrelated signal Sc1to the estimated echo paths.

The second filter unit722receives the second channel decorrelated signal Sc2and estimates echo paths through which the L-channel audio signal Sout2is output. Then, the second filter unit722generates a second estimated acoustic signal Sp2corresponding to the second channel decorrelated signal Sc2by applying the second channel decorrelated signal Sc2to the estimated echo paths.

The adder771subtracts the second channel decorrelated signal Sc2from an output signal of the microphone740. The adder772subtracts the first channel decorrelated signal Sc1from an output signal of the adder771. Although the two adders771and772are included in the processor770inFIG. 7, one adder may be used to subtract the first and second channel decorrelated signals Sc1and Sc2from the output signal of the microphone740.

FIG. 8is a flowchart illustrating an audio signal processing method800according to an exemplary embodiment. The audio signal processing method800may be performed by the audio apparatus200or300or the electronic apparatus600or700. Hereinafter, the audio signal processing method800is described with reference to the audio apparatus200.

Referring toFIG. 8, in operation810, a multi-channel signal including audio signals is received. Operation810may be performed by the decorrelator210.

In operation820, a phase shifting value is adjusted based on a correlation difference between the audio signals included in the multi-channel signal received in operation810. Operation820may be performed by the decorrelator210.

In operation830, decorrelated signals are generated by applying the phase shifting value adjusted in operation820to the audio signals included in the multi-channel signal. Operation830may be performed by the decorrelator210.

The decorrelated signals generated in operation830may be output through the plurality of speakers included in the speaker set250.

Operations of the audio signal processing method800are the same as an operation of the audio apparatus200or300or the electronic apparatus600or700. Thus, a detailed description thereof is omitted.

FIG. 9is a flowchart illustrating an audio signal processing method900according to an exemplary embodiment. The audio signal processing method900may be performed by the audio apparatus300or the electronic apparatus600or700. Hereinafter, the audio signal processing method900is described with reference to the audio apparatus300.

Referring toFIG. 9, since operation910is the same as operation810, a detailed description thereof is omitted. Hereinafter, a description is provided by assuming that a multi-channel signal, including first and second channel audio signals, is received.

In operation920, the multi-channel signal received in operation910is divided into a plurality of sub-bands. In detail, the first and second channel audio signals are divided into the plurality of sub-bands, and first and second channel sub-audio signals are generated in each of the plurality of sub-bands. Operations910and920may be performed by the pre-processor320.

In operation930, a phase shifting value in a predetermined sub-band is adjusted based on a phase difference between the first and second channel sub-audio signals in the predetermined sub-band. Operation930may be performed by the decorrelation processor330.

In operation940, first and second sub-decorrelated signals are generated by applying the phase shifting value in the predetermined sub-band, which is generated in operation930, to the first and second channel sub-audio signals in the predetermined sub-band. Operation940may be performed by the decorrelation processor330.

In operation950, first and second decorrelated signals are generated by synthesizing first and second sub-decorrelated signals generated for the plurality of sub-bands. Operation950may be performed by the synthesizer340.

The first and second decorrelated signals generated in operation950may be output through the first and second speakers351and352included in the speaker set350.

Operations of the audio signal processing method900are the same as an operation of the audio apparatus300or the electronic apparatus600or700. Thus, a detailed description thereof is omitted.

In operation1010, a phase shifting value is set based on sub-bands.

In operation1020, a weighting value is set based on sub-bands.

In operation1030, a corrected phase shifting value is set by multiplying the phase shifting value set in operation1010by the weighting value set in operation1020.

Since an operation of setting the corrected phase shifting value has been described in detail with reference toFIGS. 5A and 5B, a detailed description thereof is omitted.

As described above, according to an audio signal processing method according to one or more exemplary embodiments, an audio apparatus using the same, and an electronic apparatus using the same, decorrelated signals corresponding to audio signals included in a multi-channel signal are generated based on a correlation between the audio signals. Thus, the audio signals along predetermined echo paths without divergence of an echo filter may be correctly estimated. Accordingly, an accuracy of voice recognition may increase.