A reverberant sound adding apparatus includes a noise generator configured to generate a noise, an impulse noise generator configured to generate an impulse noise comprising an impulse sequence with random time intervals, an addition noise generator configured to generate an addition noise by adding the noise to the impulse noise, an impulse response generator configured to generate a modified impulse response by multiplying the addition noise by an amplitude characteristic of an impulse response that indicates acoustic characteristics of a space, and an impulse response convolver configured to convolve an input audio signal with the modified impulse response.