Check out this crazy internal baffle structure of this cool Fostex FE206En Back-Loaded Horn Loudspeaker.
 “The back-loaded or rear-loaded horn loudspeaker system is like bass-reflex and double bass-reflex speaker types in that the sound radiated from the back of speaker transducer is utilized to enhance the bass response. The difference however is that back-loaded horn (BLH) speaker enclosures make among the most efficient use of the back wave from the speaker driver. The back-loaded horn speaker enclosure operates by developing the bass response using the back wave from the speaker driver and an expanding horn section. The remainder of sound spectrum (mid and high-frequency ranges) is radiated directly from the front wave produced by the speaker driver. Back-loaded horn speaker enclosures are generally amongst the most efficient enclosure systems and respond well to the subtlest components of music signals. For “tighter” sound reproduction, you can reduce the interior volume of the horn speaker cabinet using fill material. Sound absorbing material should be used directly behind the driver and also at the mouth of the horn to smooth out the frequency response.”
