Main speakers are arranged on the enclosure front surface of an electronic piano.
Auxiliary speakers (18L, 18R) are arranged on the rear surface of
the enclosure. Microphones are arranged in close proximity of the main speakers.
A performance sound is regenerated from the main speakers. The regenerated sound
from the main speakers is picked up by microphones (20L, 20R). FIR
filters are used to generate the reflected signal of a picked-up sound signal from
the microphones. The generated reflected sound signal is regenerated from auxiliary speakers.
