An electronic device comprising: a reception unit configured to receive an audio signal; a bandwidth change unit configured to gradually change a bandwidth of the received audio signal from a first bandwidth to a second bandwidth during a preset time, when the received audio signal is changed; an audio output unit configured to output the received audio signal, wherein the bandwidth change unit comprises: a bandwidth expansion unit configured to, when the received audio signal is changed from a wideband signal to a narrowband signal, expand the bandwidth of the received audio signal to the first bandwidth and gradually reduce the bandwidth of the received audio signal to the second bandwidth during the preset time; and a bandwidth reduction unit configured to, when the received audio signal is changed from the narrowband signal to the wideband signal, reduce the bandwidth of the received audio signal to the first bandwidth and gradually increase the bandwidth of the received audio signal to the second bandwidth during the preset time, wherein, when the bandwidth expansion unit is operable, the first bandwidth corresponds to the wideband signal and the second bandwidth corresponds to the narrowband signal, wherein, when the bandwidth reduction unit is operable, the first bandwidth corresponds to the narrowband signal and the second bandwidth corresponds to the wideband signal, characterised in that the bandwidth expansion unit is configurable by a user to expand the bandwidth of the narrowband signal and then gradually recover the original bandwidth of the narrowband signal or to continue to expand the bandwidth of the narrowband signal. a reception unit configured to receive an audio signal; a bandwidth change unit configured to gradually change a bandwidth of the received audio signal from a first bandwidth to a second bandwidth during a preset time, when the received audio signal is changed; an audio output unit configured to output the received audio signal, wherein the bandwidth change unit comprises: a bandwidth expansion unit configured to, when the received audio signal is changed from a wideband signal to a narrowband signal, expand the bandwidth of the received audio signal to the first bandwidth and gradually reduce the bandwidth of the received audio signal to the second bandwidth during the preset time; and a bandwidth reduction unit configured to, when the received audio signal is changed from the narrowband signal to the wideband signal, reduce the bandwidth of the received audio signal to the first bandwidth and gradually increase the bandwidth of the received audio signal to the second bandwidth during the preset time, wherein, when the bandwidth expansion unit is operable, the first bandwidth corresponds to the wideband signal and the second bandwidth corresponds to the narrowband signal, wherein, when the bandwidth reduction unit is operable, the first bandwidth corresponds to the narrowband signal and the second bandwidth corresponds to the wideband signal, characterised in that the bandwidth expansion unit is configurable by a user to expand the bandwidth of the narrowband signal and then gradually recover the original bandwidth of the narrowband signal or to continue to expand the bandwidth of the narrowband signal. a bandwidth expansion unit configured to, when the received audio signal is changed from a wideband signal to a narrowband signal, expand the bandwidth of the received audio signal to the first bandwidth and gradually reduce the bandwidth of the received audio signal to the second bandwidth during the preset time; and a bandwidth reduction unit configured to, when the received audio signal is changed from the narrowband signal to the wideband signal, reduce the bandwidth of the received audio signal to the first bandwidth and gradually increase the bandwidth of the received audio signal to the second bandwidth during the preset time, wherein, when the bandwidth expansion unit is operable, the first bandwidth corresponds to the wideband signal and the second bandwidth corresponds to the narrowband signal, wherein, when the bandwidth reduction unit is operable, the first bandwidth corresponds to the narrowband signal and the second bandwidth corresponds to the wideband signal, characterised in that the bandwidth expansion unit is configurable by a user to expand the bandwidth of the narrowband signal and then gradually recover the original bandwidth of the narrowband signal or to continue to expand the bandwidth of the narrowband signal.