Signal processing apparatus and non-transitory computer readable medium

1. A signal processing apparatus comprising:

an acquisition unit configured to acquire M detection signals output from M detector devices (M is an integer equal to or greater than 2) having N-fold symmetry integer equal to or greater than 2), each of the M detector devices detecting an original signal generated from K signal sources (K is an integer equal to or greater than 2) having the N-fold symmetry; and

an application unit configured to apply a trained neural network to M input vectors corresponding to the M detection signals and output K output vectors,

wherein a same parameter is set to, of a plurality of weights included in a weight matrix of the trained neural network, weights that are commutative based on the N-fold symmetry.

2. The apparatus according to claim 1 , wherein

the detector devices are microphone devices,

the detection signals are speech signals, and

the output vectors are one of a speech spectrum, a time-frequency mask, an acoustic score, or a linguistic score.

3. The apparatus according to claim 2 , wherein

the input vectors are complex spectra, and

the plurality of weights includes complex numbers.

4. The apparatus according to claim 1 , wherein

the detector devices are microphone devices,

the detection signals are speech signals, and

the application unit applies the trained neural network to the M input vectors and outputs, as the K output vectors, K speech spectra respectively corresponding to the K signal sources.

5. The apparatus according to claim 4 , further comprising:

a speech recognition unit configured to perform speech recognition on the K speech spectra and output K sets of text data relating to speech content.

6. The apparatus according to claim 1 , wherein

the detector devices are microphone devices,

the detection signals are speech signals, and

the application unit applies the trained neural network to the M input vectors and outputs, as the K output vectors, K acoustic scores respectively corresponding to the K signal sources.

7. The apparatus according to claim 6 , further comprising:

a speech recognition unit configured to perform speech recognition on the K acoustic scores and output K sets of text data relating to speech content.

8. The apparatus according to claim 4 , further comprising:

an A/D conversion unit configured to perform A/D conversion on the M detection signals to convert them into M digital signals; and

a Fourier transform unit configured to perform short-term Fourier transform on the M digital signals to generate M frequency spectra as the M input vectors.

9. The apparatus according to claim 6 , further comprising:

an A/D conversion unit configured to perform A/D conversion on the M detection signals to convert them into M digital signals; and

a Fourier transform unit configured to perform short-term Fourier transform on the M digital signals to generate M frequency spectra as the M input vectors.

10. The apparatus according to claim 1 , wherein a first direction range in which, of K direction ranges respectively corresponding to the K signal sources when viewed from the M detector devices, two or more signal sources are present, original signals are produced with time intervals therebetween from the two or more signal sources included in the first direction range.

11. The apparatus according to claim 1 , wherein

the trained neural network includes:

M input channels into which the M input vectors are input respectively, and

K output channels which output the K output vectors respectively, and

if the correspondence between the M input vectors and the M input channels is changed by rotating the M detector devices in such a manner that the M detector devices overlap according to the N-fold symmetry, the correspondence between the K output vectors and the K output channels is changed before and after the rotation, whereas the K output vectors remain unchanged before and after the rotation.

12. A signal processing apparatus comprising:

a signal processing unit configured to train a neural network into which M input vectors corresponding to M detector devices having N-fold symmetry are input (M is an integer equal to or greater than 2, and N is an integer equal to or greater than 2) and which outputs K output vectors corresponding to K signal sources having N-fold symmetry (K is an integer equal to or greater than 2);

a determination unit configured to determine a combination of commutative weights, among a plurality of weights included in a weight matrix of the neural network, in terms of a symmetrical operation based on an order of rotational symmetry N based on a number of microphone devices M, a number of speakers K, and the order of rotational symmetry N; and

a training unit configured to assign a same parameter to multiple weights belonging to a same weight combination and train the neural network, and generate a trained neural network.

13. The apparatus according to claim 12 , wherein

the training unit trains the neural network based on training data,

the training data has training data of a plurality of speech patterns corresponding to combinations of the K signal sources, and

of the plurality of speech patterns, speech patterns having the N-fold symmetry share a same speech pattern.

14. A non-transitory computer readable medium storing instructions that cause a computer to:

output K output vectors corresponding to K signal sources having N-fold symmetry based on an input of M input vectors corresponding to M detector devices having N-fold symmetry (each of M, N, and K is an integer equal to or greater than 2) applied to a neural network,

wherein a same parameter is set to, of multiple weights included in a weight matrix of the neural network, weights that are commutative based on the N-fold symmetry.