Transfer function generation apparatus, transfer function generation method, and program
A transfer function generation apparatus includes: a modeling part that models, using a function which uses an arrival direction of a sound source as a non-discrete argument, a plurality of acoustic transfer functions to a microphone from sound sources present in a plurality of directions and that stores the modeled function; and a transfer function generation part that generates a transfer function of an arbitrary direction by using the modeled and stored function.
1. A transfer function generation apparatus, comprising:
a modeling part that models, using a function which uses an arrival direction of a sound source as a non-discrete argument, a plurality of acoustic transfer functions to a microphone from sound sources present in a plurality of directions and that stores the modeled function; and
a transfer function generation part that generates a transfer function of an arbitrary direction by using the modeled and stored function.
2. The transfer function generation apparatus according to claim 1 ,
wherein in the modeling of the transfer function, the modeling part uses a transfer function from the sound source to a reference microphone among a plurality of microphones as a reference transfer function, generates a transfer function that represents an amplitude ratio and a phase difference relative to the reference transfer function as a relative transfer function by dividing a transfer function to a different target microphone than the reference microphone among the plurality of microphones by the reference transfer function, and stores the relative transfer function as the modeled function.
3. The transfer function generation apparatus according to claim 1 ,
wherein the modeling part formulates the modeling of the transfer function by Fourier series expansion of one dimension or two or more dimensions using one arrival direction or two or more arrival directions as a main argument.
4. The transfer function generation apparatus according to claim 3 ,
wherein the modeling part obtains, as a coefficient of the modeling by the Fourier series expansion, the coefficient by which a sum of squares of a modeling error becomes minimum, and a square norm of the coefficient of the modeling becomes minimum.
5. The transfer function generation apparatus according to claim 4 ,
wherein the modeling part obtains the coefficient of the modeling by using a Moore-Penrose pseudo-inverse matrix from transfer functions from arbitrary two or more directions.
6. The transfer function generation apparatus according to claim 1 ,
wherein intervals of arrival angles of a plurality of acoustic transfer functions to one or more microphones from the sound sources present in the plurality of directions are not equal to each other.
7. A transfer function generation method, comprising:
by way of a modeling part, modeling, using a function which uses an arrival direction of a sound source as a non-discrete argument, a plurality of acoustic transfer functions to a microphone from sound sources present in a plurality of directions and storing the modeled function; and
by way of a transfer function generation part, generating a transfer function of an arbitrary direction by using the modeled and stored function.
8. A computer-readable non-transitory recording medium which includes a program that causes a computer of a transfer function generation apparatus to execute:
modeling, using a function which uses an arrival direction of a sound source as a non-discrete argument, a plurality of acoustic transfer functions to a microphone from sound sources present in a plurality of directions and storing the modeled function; and
generating a transfer function of an arbitrary direction by using the modeled and stored function.
9. The transfer function generation apparatus according to claim 2 ,
wherein the modeling part formulates the modeling of the transfer function by Fourier series expansion of one dimension or two or more dimensions using one arrival direction or two or more arrival directions as a main argument.
10. The transfer function generation apparatus according to claim 9 ,
wherein the modeling part obtains, as a coefficient of the modeling by the Fourier series expansion, the coefficient by which a sum of squares of a modeling error becomes minimum, and a square norm of the coefficient of the modeling becomes minimum.
11. The transfer function generation apparatus according to claim 10 ,
wherein the modeling part obtains the coefficient of the modeling by using a Moore-Penrose pseudo-inverse matrix from transfer functions from arbitrary two or more directions.
12. The transfer function generation apparatus according to claim 2 ,
wherein intervals of arrival angles of a plurality of acoustic transfer functions to one or more microphones from the sound sources present in the plurality of directions are not equal to each other.
13. The transfer function generation apparatus according to claim 3 ,
wherein intervals of arrival angles of a plurality of acoustic transfer functions to one or more microphones from the sound sources present in the plurality of directions are not equal to each other.
14. The transfer function generation apparatus according to claim 4 ,
wherein intervals of arrival angles of a plurality of acoustic transfer functions to one or more microphones from the sound sources present in the plurality of directions are not equal to each other.
15. The transfer function generation apparatus according to claim 5 ,
wherein intervals of arrival angles of a plurality of acoustic transfer functions to one or more microphones from the sound sources present in the plurality of directions are not equal to each other.