Head related transfer function generation apparatus, head related transfer function generation method, and sound signal processing apparatus

1. A head related transfer function generation apparatus comprising:

a first input unit that inputs a first head related transfer function generated in a first measurement environment that includes a dummy head;

a second input unit that inputs a second head related transfer function generated in a second measurement environment that is free of a dummy head; and

a transform normalization processing unit that:

generates a normalized gain by normalizing a first gain of the first head related transfer function represented in frequency-axis data with a second gain of the second head related transfer function represented in frequency-axis data, and

reduces emphasis of a sound signal by performing a dimension transformation of the normalized gain from power to voltage by calculating a square root of the normalized gain.

2. The head related transfer function generation apparatus according to claim 1 ,

wherein the first and second head related transfer functions are generated with regard to only direct waves in the first and second measurement environments.

3. The head related transfer function generation apparatus according to claim 1 ,

wherein the first and second gains are radius vectors of the first and second head related transfer functions transformed in polar coordinates, and

wherein the transform normalization processing unit divides the radius vector of the first head related transfer function by the radius vector of the second head related transfer function and also calculates a square root thereof and the transform normalization processing unit subtracts a deflection angle of the second head related transfer function from a deflection angle of the first head related transfer function.

4. The head related transfer function generation apparatus according to claim 3 ,

wherein the transform normalization processing unit divides the radius vector of the first head related transfer function by the radius vector of the second head related transfer function and thereafter calculates a square root thereof.

5. The head related transfer function generation apparatus according to claim 3 ,

wherein the transform normalization processing unit calculates square roots of each of the radius vector of the first head related transfer function and the radius vector of the second head related transfer function and thereafter divides the square root of the radius vector of the first head related transfer function by the square root of the radius vector of the second head related transfer function.

6. The head related transfer function generation apparatus according to claim 1 ,

wherein the first head related transfer function relates to a direct wave to sound pickup units installed at locations of ears of the listener from a sound source installed at a predetermined sound source direction position and is a head related transfer function in a state in which the listener or a predetermined dummy head exists, and

wherein the second head related transfer function relates to a direct wave from the sound source to the sound pickup units and is a transfer characteristic in a pristine state where the listener or the dummy head does not exist.

7. The head related transfer function generation apparatus according to claim 1 ,

wherein the first head related transfer function is a head related transfer function related to a direct wave to sound pickup units installed at locations of ears of the listener from a sound source installed at a first sound source direction position, and

wherein the second head related transfer function is a head related transfer function related to a direct wave from the sound source installed at a second sound source direction position different from the first sound source direction position to the sound pickup units.

8. The head related transfer function generation apparatus according to claim 7 ,

wherein the first head related transfer function relates to the direct wave from the sound source installed at the first sound source direction position to the sound pickup units and is normalized with a pristine state transfer characteristic in a state in which the listener or a dummy head does not exist, and

wherein the second head related transfer function relates to the direct wave from the sound source installed at the second sound source direction position to the sound pickup units and is normalized with a pristine state transfer characteristic in the state in which the listener or the dummy head does not exist.

9. A head related transfer function generation method comprising:

inputting a first head related transfer function generated in a first measurement environment that includes a dummy head and a second head related transfer function generated in a second measurement environment that is free of a dummy head;

generating a normalized gain by normalizing a first gain of the first head related transfer function represented in frequency-axis data with a second gain of the second head related transfer function represented in frequency-axis data; and

reducing emphasis of a sound signal by performing a dimension transformation of the normalized gain from power to voltage by calculating a square root of the normalized gain.

10. A sound signal processing apparatus comprising:

a first input unit that inputs a first head related transfer function generated in a first measurement environment that includes a dummy head;

a second input unit that inputs a second head related transfer function generated in a second measurement environment that is free of a dummy head;

a transform normalization processing unit that:

generates a normalized gain by normalizing a first gain of the first head related transfer function represented in frequency-axis data with a second gain of the second head related transfer function represented in frequency-axis data, and

reduces emphasis of a sound signal by performing a dimension transformation of the normalized gain from power to voltage by calculating a square root of the normalized gain to generate a transform normalized gain;

a head related transfer function generation unit that generates a normalized head related transfer function represented in time-axis data on the basis of the transform normalized gain; and

a convolution processing unit that convolves the normalized head related transfer function to a sound signal.

11. The sound signal processing apparatus according to claim 10 ,

wherein the first and second head related transfer functions are generated with respect to only direct waves in the first and second measurement environments.

12. The sound signal processing apparatus according to claim 11 , further comprising:

a second transform normalization processing unit that normalizes a first reflection gain of a first reflection head related transfer function represented in frequency-axis data with a second reflection gain of a second reflection head related transfer function represented in frequency-axis data, wherein the first and second reflection head related transfer functions are generated with regard to a reflection wave in the first and second measurement environments, and also calculates a square root of the normalization result to generate a transform normalized reflection gain; and

a second head related transfer function generation unit that generates a normalized reflection head related transfer function represented in time-axis data on the basis of the transform normalized reflection gain,

wherein the convolution processing unit convolves the normalized head related transfer function and the normalized reflection head related transfer function to the sound signal.