Apparatus and method for localizing a sound image, and a non-transitory computer readable medium

1. An apparatus for localizing a sound image, comprising:

a storage unit to store a plurality of acoustic transfer characteristics corresponding to respective different combinations of a sound image direction and an emphasis degree of feeling of localization, the emphasis degree representing a change amount of a sound pressure level of a virtual sound heard along the sound image direction if the sound image direction changes;

an input unit that receives direction indication information and emphasis degree indication information from a listener;

a selection unit that selects a suitable acoustic transfer characteristic from the plurality of acoustic transfer characteristics, the suitable acoustic transfer characteristic being determined by the selection unit to be most matched with the sound image direction indicated by the direction indication information and the emphasis degree indicated by the emphasis degree indication information;

a first operation unit that convolutes the suitable acoustic transfer characteristic with a first audio signal to obtain a second audio signal;

a second operation unit that calculates a phase difference and a level difference by using distance indication information to indicate a distance of the sound image, and obtains a third audio signal and a fourth audio signal by assigning the phase difference and the level difference to the second audio signal; and

an output unit that outputs the third audio signal and the fourth audio signal.

2. The apparatus according to claim 1 , wherein

the storage unit stores

a first acoustic transfer characteristic set including a first acoustic transfer characteristic corresponding to a first sound image direction and having a dip at a first frequency, and a second acoustic transfer characteristic corresponding to a second sound image direction and having a dip at a second frequency, and

a second acoustic transfer characteristic set including a third acoustic transfer characteristic corresponding to the first sound image direction and having a dip at a third frequency lower than the first frequency, and a fourth acoustic transfer characteristic corresponding to the second sound image direction and having a dip at a fourth frequency lower than the second frequency, and

the selection unit selects one of the first acoustic transfer characteristic set or the second acoustic transfer characteristic set by using the emphasis degree indication information to yield a selected acoustic transfer characteristic set, and selects the suitable acoustic transfer characteristic corresponding to the sound image direction indicated by the direction indication information from the selected acoustic transfer characteristic set.

3. The apparatus according to claim 1 , wherein

the first operation unit convolutes the suitable acoustic transfer characteristic of a part of a frequency band with the first audio signal.

4. A method for localizing a sound image, comprising:

storing a plurality of acoustic transfer characteristics corresponding to respective different combinations of a sound image direction and an emphasis degree of feeling of localization into a storage unit, the emphasis degree representing a change amount of a sound pressure level of a virtual sound heard along the sound image direction if the sound image direction changes;

inputting direction indication information and emphasis degree indication information by a listener;

selecting a suitable acoustic transfer characteristic from the plurality of acoustic transfer characteristics, wherein the selecting is based on a determination that the suitable acoustic transfer characteristic is most matched with the sound image direction indicated by the direction indication information and the emphasis degree indicated by the emphasis degree indication information;

convoluting the suitable acoustic transfer characteristic with a first audio signal to obtain a second audio signal;

calculating a phase difference and a level difference by using distance indication information to indicate a distance of the sound image;

obtaining a third audio signal and a fourth audio signal by assigning the phase difference and the level difference to the second audio signal; and

outputting the third audio signal and the fourth audio signal.

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

calculating a phase difference and a level difference by using distance indication information to indicate a distance of the sound image; and

obtaining a third audio signal and a fourth audio signal by assigning the phase difference and the level difference to the second audio signal.

6. A non-transitory computer readable medium for causing a computer to perform a method for localizing a sound image, the method comprising:

storing a plurality of acoustic transfer characteristics corresponding to respective different combinations of a sound image direction and an emphasis degree of feeling of localization into a storage unit, the emphasis degree representing a change amount of a sound pressure level of a virtual sound heard along the sound image direction if the sound image direction changes;

inputting direction indication information and emphasis degree indication information by a listener;

selecting a suitable acoustic transfer characteristic from the plurality of acoustic transfer characteristics, the suitable acoustic transfer characteristic determined to be most matched with the sound image direction indicated by the direction indication information and the emphasis degree indicated by the emphasis degree indication information;

convoluting the suitable acoustic transfer characteristic with a first audio signal to obtain a second audio signal;

calculating a phase difference and a level difference by using distance indication information to indicate a distance of the sound image;

obtaining a third audio signal and a fourth audio signal by assigning the phase difference and the level difference to the second audio signal; and

outputting the third audio signal and the fourth audio signal.