Sound processing device, and sound processing method

A sound processing method in a sound processing apparatus that performs directivity synthesis processing of a first picked-up sound signal output from a first sound pickup unit and a second picked-up sound signal output from a second sound pickup unit, the method comprising:

• acquiring a first directional picked-up sound signal and a second directional picked-up sound signal from a directivity synthesis processing section that generates the first directional picked-up sound signal by delaying the second picked-up sound signal relative to the first picked-up sound signal and combining the first picked-up sound signal with the delayed second picked-up sound signal, and that generates the second directional picked-up sound signal by delaying the first picked-up sound signal relative to the second picked-up sound signal and combining the delayed first picked-up sound signal with the second picked-up sound signal;
• generating a non-directional level signal indicating a level of a signal obtained by adding up the first directional picked-up sound signal and the second directional picked-up sound signal;
• generating a directional level signal obtained by adding up a first level signal indicating a level of the first directional picked-up sound signal and a second level signal indicating a level of the second directional picked-up sound signal;
• acquiring a level difference between the non-directional level signal and the directional level signal;
• and
• adjusting the amount of delay in the directivity synthesis processing section so as to reduce the level difference.