Acoustic processing method, recording medium, and acoustic processing system

An acoustic processing system comprising:

• an obtainer that obtains (i) sound information related to a sound including a predetermined sound and (ii) metadata including information related to a space in which the predetermined sound is reproduced;
• an acoustic processor that performs, based on the sound information and the metadata, acoustic processing of generating a sound signal expressing a sound including an early reflection that reaches a user after a direct sound that reaches the user directly from a sound source object;
• and
• an outputter that outputs an output sound signal including the sound signal,
• wherein the acoustic processor includes:
• a parameter determiner that determines parameters for generating the early reflection, the parameters including a position, in the space, of a virtual sound source object that generates the early reflection;
• and
• an early reflection generation processor that generates the early reflection based on the parameters determined, and
• the parameters include at least a parameter that varies over time according to a predetermined condition.