A sound processing apparatus includes: a sound output unit which outputs sound based on a first sound signal as first sound processing when execution of the first sound processing is instructed; a sound collecting unit which generates an echo signal by collecting surrounding sound; a filtering unit which performs filtering process with an adaptive digital filter on the first sound signal and generates a pseudo echo signal; a subtracting unit which removes a sound component, which is output from the sound output unit and reaches the sound collecting unit, from the echo signal by subtracting the pseudo echo signal from the echo signal to generate a residual signal; an updating unit which updates the adaptive digital filter based on the residual signal and the first sound signal; and an update resolution control unit which controls the resolution at which the adaptive digital filter is updated by the updating unit.