Speaker systems generally include two or more speaker elements, each of which converts electrical energy into acoustic energy over a particular frequency range. A speaker used as an acoustic output means in an audio-video system or multi-media system comprises a main speaker part for generating sound, and a case for containing and holding the main speaker part inside. The case has a function for containing and holding the main speaker part, and for emitting the sound forward produced by the main part. It also has a function to protect the main speaker part from external force or dust to prevent mechanical or chemical damage. A normal speaker cabinet has an electro magnetically driven speaker cone sealed to an opening in the wall of a sealed cabinet. This arrangement provides a drooping frequency response curve. In some speaker systems having a speaker mounted in a speaker box, a bass reflex duct is located at a rear of the speaker inside of the speaker box. The bass reflex duct leads to a bass reflex port opened in the speaker box.
