Abstract: A cover for a portable electronic device includes a body arranged to accommodate the portable electronic device in a detachable manner and provide mechanical protection when the cover is attached to the portable electronic device, and a groove provided in a surface of the body that faces the portable electronic device. A first end of the groove serves as an audio inlet and is disposed at a location of an audio speaker, and a second end of the groove serves as an audio outlet and is disposed at an edge of the body. A cross-sectional area of the groove enlarges from the first end towards the second end to provide a sound-amplifying audio channel. The groove is open from the first end to the second end such that a back surface of the portable electronic device attached to the cover encloses the groove.