Abstract: A portable electronic device wherein a first case has a first sound radiating hole formed in the front wall thereof and positioned as opposed to a speaker and a second sound radiating hole formed in the rear wall thereof and positioned as opposed to the speaker. The two cases are rotatably joined by a hinge mechanism. The second case has a second knuckle constituting the hinge mechanism and is provided with a strip member for opening or closing the second sound radiating hole with the closing or opening movement of the second case. The strip member has a free end portion to be wound up by the second knuckle to open the second sound radiating hole when the two cases are in a closed state or to be paid out to close the second sound radiating hole when the two cases are in an opened state.

Abstract: The invention provides a portable electronic device wherein a first case has a first sound radiating hole formed in the front wall thereof and positioned as opposed to a speaker and a second sound radiating hole formed in the rear wall thereof and positioned as opposed to the speaker. The two cases are rotatably joined by a hinge mechanism. The second case has a second knuckle constituting the hinge mechanism and provided with a strip member for opening or closing the second sound radiating hole with the closing or opening movement of the second case. The strip member has a free end portion to be wound up by the second knuckle to open the second sound radiating hole when the two cases are in a closed state or to be paid out to close the second sound radiating hole when the two cases are in an opened state.