A hearing aid (51) includes: a sound collecting unit (500) configured to collect one of propagation sounds respectively output from external apparatuses; a radio wave receiving unit (560) that is an exemplary receiving unit configured to receive transmission audio signals transmitted from the respective external apparatuses; a comparing unit (550) configured to compare the propagation sound collected by the sound collecting unit (500) with each of the transmission audio signals received by the radio wave receiving unit (560), and select one of the transmission audio signals that corresponds to the propagation sound; and a sound output unit (520) configured to output, to the user, the sound obtained from the transmission audio signal selected by the comparing unit.