Information processing method, information processing device, acoustic reproduction system, and recording medium

An information processing device that generates, by processing sound information, an output sound signal for causing a user to perceive a sound as arriving from a sound source within a three-dimensional sound field that is virtual, the information processing device comprising:

• an obtainer that obtains a position of the user within the three-dimensional sound field;
• a determiner that determines a virtual boundary that includes two or more lattice points surrounding the user, based on the position of the user which has been obtained, the two or more lattice points being among a plurality of lattice points set at predetermined intervals within the three-dimensional sound field;
• a reader that reads, from a database that stores propagation characteristics of the sound from the sound source to the plurality of lattice points, the propagation characteristics of the sound from the sound source to the two or more lattice points included in the virtual boundary determined;
• a calculator that calculates transfer functions of the sound from the two or more lattice points included in the virtual boundary determined to the position of the user;
• and
• a generator that generates the output sound signal by processing the sound information using the propagation characteristics read and the transfer functions calculated.