A speaker set configured for a portable electronic device includes a hollow shell, a back cover, and a loudspeaker sandwiched between the shell of the back cover. The shell includes a first chamber, a second chamber, a third chamber and a fourth chamber. The second and third chambers are positioned at opposite sides of the first chamber, and communicate with a surrounding environment at opposite sides of the shell. The loudspeaker is accommodated in the first chamber, and divides the first chamber into a front sub-chamber and a rear sub-chamber. The front sub-chamber communicates with the second and the third chambers thereby forming a front resonance chamber. The rear sub-chamber communicates with the fourth chamber thereby forming a rear resonance chamber. Sound waves generated from the loudspeaker are transmitted to and resonate in the front and rear resonance chambers and then transmitted to the surrounding environment in opposite directions.