Patent Grant
7925504
This application is the National Phase of PCT/JP2006/300003, filed Sep. 10, 2006, which claims priority to Japanese Application No. 2005-012701, filed Jan. 20, 2005, the disclosures of which are hereby incorporated by reference in their entirety.
The present invention relates to a signal removal method, signal removal system, and signal removal program, and particularly to a signal removal method, signal removal system, and signal removal program that remove a signal coming from a particular direction.
Conventionally, a signal removal apparatus of this kind is used for removing signals arriving to the microphone from particular directions in an environment where a plurality of audio/speech signals and noise are spatially mixed. As an example of a conventional signal removal apparatus, a noise suppression apparatus for speech (voice) recognition is described in Patent Document 1. This apparatus is a signal removal apparatus capable of removing a signal even when the signal comes from a direction different from a particular direction expected or the power of a signal coming from the particular direction is close to or less than the power of signals coming from other directions.
[Patent Document 1]
Japanese Patent Kokai Publication No. JP-P2003-271191A (
The noise suppression apparatus for speech recognition described referring to
The first problem is that the apparatus cannot cancel a target voice with high accuracy when the actual direction from which a signal comes is different from the expected direction and the power of a signal coming from the particular direction is close to or less than the powers of signals coming from other directions. The reason is that this apparatus integrates the fixed beamformer 52 incapable of accurately canceling a target voice when an actual direction from which a signal comes is different from a direction expected as a particular direction and the adaptive beamformer 51 incapable of accurately canceling a target voice when the power of the signal coming from the particular direction is close to or less than the powers of signals coming from other directions.
The second problem is that the fixed beamformer cannot accurately cancel a target voice when there are gain differences between a plurality of microphones. The reason is that, since the fixed beamformer cancels a target voice by manipulating the phases and having waveforms of opposite phases overlap with each other, the waveforms cannot be canceled if the amplitudes of the waveforms are different even when the phases are completely inverted (when the particular direction expected and the actual direction from which the signal comes coincide).
Therefore, it is an object of the present invention to provide a signal removal method, signal removal system, and signal removal program that remove a signal coming from a particular direction with higher accuracy.
The present invention for achieving the object is summarized as follows.
A method relating to an aspect of the present invention is a method in which a signal removal device removes a signal arriving at sensors from a particular direction using signals from a plurality of the sensors. This method comprises: removing a signal coming from a particular direction by a first beamformer that steers a null to the particular direction using signals from the plurality of sensors; calculating a coefficient for correcting the gain of the spectrum of a signal outputted from one of the plurality of sensors according to the directivity characteristic of the first beamformer; correcting the gain of the spectrum of the signal from the one sensor by the calculated correction coefficient; and correcting to reduce an output signal spectrum of the first beamformer by the corrected signal spectrum, wherein the step of the calculating a coefficient calculates the correction coefficient such that the gain at a direction within a predetermined range relating to the particular direction agrees to the first beamformer.
A method relating to another aspect of the present invention is a method in which a signal removal device removes a signal arriving at sensors from a particular direction using signals from a plurality of the sensors. This method comprises: removing a signal coming from a particular direction by a first beamformer that steers a null to the particular direction using signals from the plurality of sensors; deriving a signal spectrum from the sensor signals by a second beamformer that forms a second directivity characteristic different from a first directivity characteristic of the first beamformer of the plurality of sensors; calculating a coefficient for correcting the gain of the spectrum of a signal outputted from the second beamformer according to the first directivity characteristic and the second directivity characteristic; correcting the spectrum of the signal outputted from the second beamformer by the calculated correction coefficient; and correcting to reduce an output signal spectrum of the first beamformer by the corrected output signal spectrum of the second beamformer, wherein the step of the calculating a coefficient calculates the correction coefficient such that the gain at a direction within a predetermined range relating to the particular direction agrees to the first beamformer.
In a first development mode of the method relating to the present invention, when the spectrum of the signal outputted from the first beamformer is corrected, subtraction may be performed on a remaining signal or signals after the removal by the first beamformer.
In a second development mode of the method relating to the present invention, the gains of the plurality of sensors may be adjusted frequency by frequency.
In a third development mode of the method relating to the present invention, the steps other than the step in which the spectrum is corrected may be processed in a time domain.
In a fourth development mode of the method relating to the present invention, the gain of the signal with the corrected spectrum may be restored.
A signal removal device relating to an aspect of the present invention, which removes a signal arriving at sensors from a particular direction using signals from a plurality of the sensors. This device comprises: a first beamformer that removes a signal coming from a particular direction by steering a null to the particular direction, using signals from the plurality of sensors; a coefficient calculation unit that calculates a coefficient for correcting the gain of the spectrum of a signal outputted from one of the plurality of sensors according to the directivity characteristic of the first beamformer; a gain correction unit that corrects the spectrum of the signal from the one sensor by the calculated correction coefficient; and a spectrum correction unit that corrects to reduce an output signal spectrum of the first beamformer by the corrected sensor signal spectrum, wherein the coefficient calculation unit calculates the correction coefficient such that the gain at a direction within a predetermined range relating to the particular direction agrees to the first beamformer.
A signal removal device relating to another aspect of the present invention, which removes a signal arriving at sensors from a particular direction using signals from a plurality of the sensors. This device comprises: a first beamformer that removes a signal coming from a particular direction by steering a null to the particular direction using signals from the plurality of sensors; a second beamformer that forms a second directivity characteristic different from a first directivity characteristic of the first beamformer; a coefficient calculation unit that calculates a coefficient for correcting the gain of the spectrum of a signal outputted from the second beamformer according to the first directivity characteristic and the second directivity characteristic; a gain correction unit that corrects the spectrum of the signal outputted from the second beamformer by the calculated correction coefficient; and a spectrum correction unit that corrects to reduce an output signal spectrum of the first beamformer by the corrected output signal spectrum of the second beamformer, wherein the coefficient calculation unit calculates the correction coefficient such that the gain at a direction with a predetermined range relating to the particular direction agrees to the first beamformer.
In a first development mode of the signal removal device relating to the present invention, the spectrum correction unit may perform subtraction on a remaining signal or signals after the removal by the first beamformer.
A second development mode of the signal removal device relating to the present invention may further comprise a gain adjustment unit that adjusts the gains of the plurality of sensors frequency by frequency.
In a third development of the signal removal device relating to the present invention, the processings other than a processing of the spectrum correction unit may be performed in a time domain.
A fourth development of the signal removal device relating to the present invention may include a gain restoration unit that restores the gain of the signal with the corrected spectrum.
A program relating to an aspect of the present invention has a computer, constituting a device that removes a signal arriving at sensors from a particular direction using signals from a plurality of the sensors, perform the following processings. This program comprises: removing a signal coming from a particular direction by a first beamformer that steers a null to the particular direction using signals from the plurality of sensors; calculating a coefficient for correcting the gain of the spectrum of a signal outputted from one of the plurality of sensors according to the directivity characteristic of the first beamformer; correcting the gain of the spectrum of the signal from the sensor by the calculated correction coefficient; and correcting to reduce an output signal spectrum of the first beamformer by the corrected signal spectrum, wherein the processing of calculating a coefficient calculates the correction coefficient such that the gain at a direction within a predetermined range relating to the particular direction agrees to the first beamformer.
A program relating to another aspect of the present invention has a computer, constituting a device that removes a signal arriving at sensors from a particular direction using signals from a plurality of the sensors, perform the following processing. This program comprises: removing a signal coming from a particular direction by a first beamformer that steers a null to a particular direction using signals from the plurality of sensors; deriving a signal spectrum from the sensor signals of the plurality of sensors using a second beamformer that forms a second directivity characteristic different from a first directivity characteristic of the first beamformer; calculating a coefficient for correcting the gain of the spectrum of a signal outputted from the second beamformer according to the first directivity characteristic and the second directivity characteristic; correcting the spectrum of the signal outputted from the second beamformer by the calculated correction coefficient; and correcting to reduce an output signal spectrum of the first beamformer by the corrected output signal spectrum of the second beamformer, wherein the processing of calculating a coefficient calculates the correction coefficient such that the gain at a direction within a predetermined range relating to the particular direction agrees to the first beam former.
According to the present invention, a signal coming from a particular direction can be accurately removed by removing a remaining signal or signals (caused by a difference between a direction expected as a particular direction and an actual direction from which the signal comes) included in a signal after the processing of a beamformer, which steers a null to the particular direction, by spectrum correction even when there is a difference between a direction expected as the particular direction and an actual direction from which the signal comes, and when the power of a signal coming from the particular direction is close to or less than the power(s) of signal(s) coming from other direction(s). The reason is that, in the present invention, the spectrum of the remaining signal(s) after the processing of the beamformer is estimated using a correction coefficient calculated from the directivity characteristic of the beamformer and is removed by spectrum correction.
Further, according to the present invention, by adjusting a gain difference between the sensors before the processing of the beamformer that steers a null to a particular direction, the beamformer that steers the null to the particular direction can be made more accurate. The reason is that the present invention is configured so that the gain difference between the sensors is adjusted frequency by frequency before the processing of the beamformer.
Examples of the present invention will be described in detail with reference to the attached drawings.
Xq(f,t) is a plurality of sensor signals received by the beamformer 1. Note that q represents the channel number (there are only two channels in
Xq(f,t) is a plurality of sensor signals, which are a mixture of a plurality of signals Sk(f,t) (K number of signals) arriving at the sensors from various directions, and is modeled using the following formulae (1) and (2):
X1(f,t)=Σ—{k=1˜K}exp{j2πf(fs/N)(dsin θk(t)/c)}Sk(f,t) Formula (1)
X2(f,t)=Σ—{k=1˜K}exp{j2πf(fs/N)(−dsin θk(t)/c)}Sk(f,t) Formula (2)
Note that Σ_{k=1˜K} represents the summation of k=1˜K. Further, fs represents the sampling frequency; d represents ½ of the distance between the sensors; θk(t) represents the direction in which the signal Sk(f,t) comes; and c represents the propagation speed of the signal.
The beamformer 1 removes a signal (or signals) coming from a particular (specific) direction θ(t) by steering a null to the direction θ(t) (step S1 in
Y(f,t)=W1(f,t)X1(f,t)+W2(f,t)X2(f,t) Formula (3)
Y(f,t) represents the output signal of the beamformer 1. Wq(f,t) represents the filter coefficient of the beamformer 1 and can be given, for instance, by the following formulae (4) and (5):
W1(f,t)=0.5 exp{−j2πf(fs/N)(dsin θ(t)/c)} Formula (4)
W2(f,t)=−0.5 exp{−j2πf(fs/N)(−dsin θ(t)/c)} Formula (5)
Here, by substituting the formulae (1), (2), (4), and (5) into the formula (3) and rearranging it, a formula (6) is given:
Y(f,t)=jΣ—{k=1˜K}sin{2πf(fs/N)(d/c)(sin θk(t)−sin θ(t))}Sk(f,t) Formula (6)
Further, assuming that the signals Sk(f,t) for various k are uncorrelated to each other, the output signal spectrum |Y(f,t)| of the beamformer 1 is given by the following formula (7):
|Y(f,t)|=sqrt(Σ—{k=1˜K}sin ^2{2πf(fs/N)(d/c)(sin θk(t)−sin θ(t))}|Sk(f,t)|^2) Formula (7)
Here, sqrt(x) represents the square-root operation of x and x^2 represents the square operation of x. In the formula (7), the content of the sqrt parentheses is the summation of value obtained by multiplying |Sk(f,t)|^2 by a weight sin ^2{2πf(fs/N)(d/c)(sin θk(t)−sin θ(t))} for k{k=1˜K}.
For instance, as shown in
D1(f,θk(t),θ(t))=sqrt(sin ^2{2πf(fs/N)(d/c)(sin θk(t)−sin θ(t))}) Formula (8)
As indicated in
In order to accurately remove a signal (or signals) even when an actual direction ((θk((t)) from which the signal comes is different from the direction (θ(t)=0[degree] in this example) the beamformer 1 expects unwanted signals to come from, a spectrum correction processing, described below, is performed.
The coefficient calculation unit 3 determines how much shift from the direction expected by the beamformer 1 (θ(t)=0[degree] in this example) is permitted, and calculates the coefficient α(f,t) for correcting the gains of the spectra of the sensor signals according to the directivity characteristic 1 of the formula (8) (step S2 in
α(f,t)=D1(f,θ(t)+10, θ(t)) Formula (9)
The gain correction unit 4 corrects the spectrum |Xq(f,t)|(q=1 or 2) of the sensor signal according to the correction coefficient α(f,t) calculated by the coefficient calculation unit 3 (step S3 in
α(f,t)|Xq(f,t)|>=|Y(f,t)| (in the case where 0−10<=θk(t)<=0+10) Formula (10)
α(f,t)|Xq(f,t)|<|Y(f,t)| (in all other cases) Formula (11)
The spectrum correction unit 5 corrects the output signal spectrum of the beamformer 1 according to the output signal spectrum α(f,t)|Xq(f,t)| of the gain correction unit 4 as shown in a formula (12) (step S4 in
|Z(f,t)|=max[|Y(f,t)|−α(f,t)|Xq(f,t)|, floor] Formula (12)
Note that “floor” represents a flooring value for preventing the spectrum value from being negative and may be freely set within a range of 0 to |Y(f,t)|.
By the formulae (10) to (12), signals coming from the directions θ(t)=0±10 are removed.
Next, the function and effect of the first example of the present invention will be described. In the present example, even when an actual direction from which a signal comes is different from an direction expected by the beamformer 1, the signal coming from a particular direction can be accurately removed by correcting the spectrum of the sensor signal by the correction coefficient calculated according to the directivity characteristic of the beamformer 1 and correcting the output signal spectrum of the beamformer 1 by the corrected sensor signal spectrum at a stage downstream of the beamformer 1.
Referring to
The beamformer 1 processes a plurality of sensor signals as described in the first example. The beamformer 2 processes a plurality of sensor signals so that it forms a different directivity characteristic from the beamformer 1, and its output signal is expressed by a formula (13):
X′(f,t)=W1 (f,t)X1(f,t)+W′2(f,t)X2(f,t) Formula (13)
X′(f,t) represents the output signal of the beamformer 2. W′q(f,t) represents the filter coefficient of the beamformer 2 and can be expressed by the following formulae (14) and (15):
W′1(f,t)=0.5 exp{−j2πf(fs/N)(dsin θ(t)/c)} Formula (14)
W′2(f,t)=0.5 exp{−j2πf(fs/N)(−dsin θ(t)/c)} Formula (15)
Here, by substituting the formulae (1), (2), (14), and (15) into the formula (13) and rearranging it, a formula (16) is given:
X′(f,t)=Σ—{k=1˜K}cos{2πf(fs/N)(d/c)(sin θk(t)−sin θ(t))}Sk(f,t) Formula (16)
Further, assuming that the signals Sk(f,t) for various k are uncorrelated to each other, the output signal spectrum |X′(f,t)| of the beamformer 2 is given by a formula (17):
|X′(f,t)|=sqrt(Σ—{k=1˜K}cos^2{2πf(fs/N)(d/c)(sin θk(t)−sin θ(t))}|Sk(f,t)|^2) Formula (17)
In the formula (17), the content of the sqrt parentheses is the summation of values obtained by multiplying |Sk(f,t)|^2 by a weight cos^2{2πf(fs/N)(d/c)(sin θk(t)−sin θ(t))} for k{k=1˜K}. Therefore, the directivity characteristic of the beamformer 2 (the directivity characteristic 2 shown in
D2(f,θk(t),θ(t))=sqrt(cos^2{2πf(fs/N)(d/c)(sin θk(t)−sin θ(t))}) Formula (18)
The formula (18) above is different from the directivity characteristic D1(f,θk(t),θ(t)) (the directivity characteristic 1 shown in
The coefficient calculation unit 6 determines how much shift from the direction expected by the beamformer 1 (θ(t)=0[degree] in this example) is permitted, and calculates the coefficient α(f,t) for correcting the gains of the spectra of the sensor signals according to the directivity characteristic 1 and the directivity characteristic 2. For instance, when a shift of 10 degrees is permitted, a formula (19) is given:
α(f,t)=D1(f,θ(t)+10, θ(t))/D2(f,θ(t)+10, θ(t)) Formula (19)
The gain correction unit 4 corrects the output signal spectrum |X′(f,t)| of the beamformer 2 according to the correction coefficient α(f,t) calculated by the coefficient calculation unit 6. The directivity characteristic of the output signal spectrum |X′(f,t)| of the beamformer 2 is as shown in
α(f,t)|X′(f,t)|>=|Y(f,t)| (in the case where 0−10<=θk(t)<=0+10) Formula (20)
α(f,t)|X′(f,t)|<|Y(f,t)| (in all other cases) Formula (21)
The spectrum correction unit 5 corrects the output signal spectrum of the beamformer 1 according to the output signal spectrum α(f,t)|X′(f,t)| of the gain correction unit 4 as shown in a formula (22):
|Z(f,t)|=max[|Y(f,t)|−α(f,t)|X′(f,t)|, floor] Formula (22)
Next, the function and effect of the second example of the present invention will be described. In the present example, even when an actual direction from which a signal comes is different from a direction expected by the beamformer 1, the signal(s) coming from a particular direction can be accurately removed by correcting the output signal spectrum of the beamformer 2 by the correction coefficient(s) calculated according to the directivity characteristics of the beamformer 1 and the beamformer 2, and correcting the output signal spectrum of the beamformer 1 by the corrected output signal spectrum of the beamformer 2 at a stage downstream of the beamformer 1.
Further, while removing a signal coming from a particular direction, it is possible to reduce the influence of the spectrum correction processing on signals coming from other directions by selecting the filter coefficients of the beamformer 2 as indicated by the formulae (14) and (15). In other words, by varying the coefficient of the beamformer 2, it becomes possible to vary the directivity characteristic of the entire signal removal system more freely.
When there is a gain difference between the plurality of the sensor signals indicated by the formulae (1) and (2), the gain adjustment unit 7 adjusts the gain difference. For instance, the plurality of the sensor signals are modeled using formulae (23) and (24):
X1 (f,t)=Σ—{k=1˜K}exp{j2πf(fs/N)(dsin θk(t)/c)}Sk(f,t) Formula (23)
X2(f,t)=b(f)Σ—{k=1˜K}exp{j2πf(fs/N)(−dsin θk(t)/c)}Sk(f,t) Formula (24)
Note that b(f) represents the gain relating to the sensor signal X2(f,t).
Gain differences such as the one indicated by the formulae (23) and (24) are caused by actual individual differences among sensors. In order to adjust these differences, the gain adjustment unit 7 adjusts the gain frequency by frequency as indicated by a formula (25):
X2(f,t)=sqrt(<|X1(f,t)|^2>—t/<|X2(f,t)|^2>—t)X2(f,t) Formula (25)
Note that < >_t represents a temporal mean operation (it may be any type of mean operation such as moving average, mean operation using low-pass filters or order-statistics filters).
By the processing of the formula (25), b(f) in the formula (24) can be considered to be the equivalent of 1 even when there is a gain difference between the sensors, therefore the formula (24) coincides with the formula (2). As a result, the beamformer 1 becomes more accurate.
In the present example, by adjusting the gains of the plurality of sensor signals before being processed by the beamformer 1 when there is a gain difference between the sensors, the beamformer 1 can be made more accurate, enabling the entire signal removal system to accurately remove a signal coming from a particular direction.
In the present example, by adjusting the gains of the plurality of sensor signals before being processed by the beamformer 1 and the beamformer 2 when there is a gain difference between the sensors, the beamformer 1 and the beamformer 2 can be made more accurate, enabling the entire signal removal system to accurately remove a signal coming from a particular direction. Further, compared with the third example, the directivity characteristic of the entire signal removal system can be more freely varied by using the beamformer 2.
In the first to fourth examples described above, since all the processings are linear operations, other than the processing by the spectrum correction unit 5, which is a nonlinear operation in a frequency domain, the processings can be performed also in time domains by processing the multiplications in frequency domains by convolution in time domains.
Further, in the first to fourth examples, the sensor signals are modeled using the formulae (1) and (2) or (23) and (24), and the filter coefficients of the beamformer 1 that forms a null in a particular direction are expressed by the formulae (4) and (5). However, if the models of the sensor signals are different from the formulae (1) and (2), the filter coefficients of the beamformer will be different as well. Therefore, when the models of the sensor signals are different, it is possible to use different filter coefficients from the ones expressed by the formulae (4) and (5). This also applies to the beamformer 2.
Further, if the coefficients of the beamformer 1 and the beamformer 2 change, their respective directivity characteristic indicated by the formulae (8) and (18) will change as well.
Further, in the first to fourth examples, we assumed the particular direction as θ(t)=0 degree, however, it may be any other direction. Further, it is possible to vary θ(t) over time.
Further, in the first to fourth examples, the coefficient calculation unit 3 and the coefficient calculation unit 6 permit a shift of 10 degrees from the particular direction, however, the shift may be any degrees. Further, it is possible to vary the permitted range over time. When the permitted range of shift and the particular direction do not vary over time, it is possible to reduce the calculation amount by performing the calculation once and tabling the results since the coefficient values do not change, either.
The gain restoration unit 9 restores the gain of the signal removed in the signal removal unit 8. The restoration is performed according to the directivity characteristic formed by the signal removal unit 8. The directivity characteristic formed by the signal removal unit 8 can be expressed by a formula (26):
D(f,θk(t),θ(t))=D1(f,θk(t),θ(t))−α(f,t)D2(f,θk(t),θ(t)) Formula (26)
Note that, when the signal removal unit 8 is the signal removal system of the first or third example of the present invention, D2(f, θk(t),θ(t)) in the formula (26) is 1.
By using the formula (26), what direction a signal whose gain is being restored to 1 is coming from is determined, and a restoration coefficient value β(f,t) of the gain is calculated using a formula (27). For instance, when the gain of a signal coming from a direction of 15 degrees is intended to be restored to 1, the formula (27) is as follows:
β(f,t)=1.0/D(f,15,θ(t)) Formula (27)
Then the gain of the output signal spectrum |Z(f,t)| of the signal removal unit 8 is restored by β(f,t). Further, the gain restoration unit 9 outputs |Z′(f,t)| as indicated by a formula (28):
|Z′(f,t)|=min[β(f,t)|Z(f,t)|,ceil] Formula (28)
Note that ceil represents the ceiling of |Z′(f,t)| and can be set to any value such as |Xq(f,t)| and |X′q(f,t)|.
In the formula (27), it is set so that the gain of a signal coming from the direction of 15 degrees is restored to 1, however, it may be set to any other direction other than the direction of 15 degrees.
In the present example, distortion (caused by the gain difference frequency by frequency) added in the signal removal unit 8 can be reduced by having the gain restoration unit 9 restore the gain of the output signal of the signal removal unit 8.
In the present example, whether or not there is a signal coming from a particular direction can be accurately detected by providing the signal detection unit 11 at a stage downstream of the signal removal unit 10. In other words, even when signals with different powers come from various directions, a signal coming from the particular direction can be detected. This is because the signal removal unit 10 accurately removes a signal coming from the particular direction.
According to the present example, it is possible to separate signals coming from a plurality of particular directions by using the signal separation unit 12 constituted by a plurality of signal removal units.
In the present example, a signal coming from a particular direction can be accurately enhanced by providing the signal enhancement unit 13 at a stage following the signal removal unit 10. In other words, even when signals with different powers come from various directions, a signal coming from the particular direction can be enhanced. The reason is that the signal removal unit 10 accurately removes a signal coming from the particular direction, and as a result, signals coming from other directions can be inferred.
In the present example, a voice coming from a particular direction can be accurately emphasized by providing the speech enhancement unit 14 at a stage subsequent to the signal removal unit 10. In other words, even when disturbing sounds with different powers come from various directions, a voice coming from the particular direction can be emphasized. The reason is that the signal removal unit 10 accurately removes a voice coming from the particular direction, and as a result, disturbing sounds (noises) coming from other directions can be inferred.
A program 24 for signal removal, stored in the memory device 20, is read into the signal removal system 22 and controls the operation of the signal removal system 22, which is program-controlled. Controlled by the program 24 for signal removal, the signal removal system 22 executes the same processings as any one of the signal removal systems in the first to fifth examples of the present invention.
A program 27 for signal detection, stored in the memory device 20, is read into the signal detection system 25 and controls the operation of the signal detection system 25, which is program-controlled. Controlled by the program 27 for signal detection, the signal detection system 25 executes the same processings as the signal detection system of the sixth example of the present invention.
A program 30 for signal separation, stored in the memory device 20, is read into the signal separation system 28 and controls the operation of the signal separation system 28, which is program-controlled. Controlled by the program 30 for signal separation, the signal separation system 28 executes the same processings as the signal separation system of the seventh example of the present invention.
A program 33 for signal enhancement, stored in the memory device 20, is read into the signal enhancement system 31 and controls the operation of the signal enhancement system 31, which is program-controlled. Controlled by the program 33 for signal enhancement, the signal enhancement system 31 executes the same processings as the signal enhancement system of the eighth example of the present invention.
A program 36 for speech enhancement, stored in the memory device 20, is read into the speech enhancement system 34 and controls the operation of the speech enhancement system 34, which is program-controlled. Controlled by the program 36 for speech enhancement, the speech enhancement system 34 executes the same processings as the speech enhancement system of the ninth example of the present invention.
It should be noted that other objects, features and aspects of the present invention will become apparent in the entire disclosure and that modifications may be done without departing the gist and scope of the present invention as disclosed herein and claimed as appended herewith.
Also it should be noted that any combination of the disclosed and/or claimed elements, matters and/or items may fall under the modifications aforementioned.
It is possible to apply the present invention not only to the removal of sound signal, but also to the removal of radio wave, electromagnetic wave, and optical (such as infrared radiation) signals.
The present invention can be applied to various applications removing a signal arriving at sensors from a particular direction from a plurality of spatially mixed signals.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-012701 | Jan 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/300003 | 1/4/2006 | WO | 00 | 7/19/2007 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2006/077745 | 7/27/2006 | WO | A |
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