An electronic device according to various embodiments disclosed in the present document may comprise: a housing; a speaker equipped in the housing; an acoustic duct for transmitting an output of the speaker to a user; an outer hole formed in the housing to be connected to the outside of the electronic device; an outer sound duct for transmitting to the user a sound flowing in through the outer hole; and a variable hole member disposed on the outer hole and/or the outer sound duct, wherein the variable hole member may comprise: a conductive member applying an electrical signal; a vent hole through which the sound transmitted from the outer hole passes; and a transforming member transforming in accordance with the electrical signal to at least partly close the vent hole. Various other embodiments may be possible.