Unable to hear back of the head sound effects

Please clarify...are you listening to multi-channel or to stereo (2 channels, speakers in front, maybe a sub)?

It's on two channel stereo.  It is most easily heard on a pair of headphones.  It's not room reflection.

Binaural recordings do provide surround effects when listening with stereo headphones, but they still have headphone limitations.  The sound still seems tobe in one’s head to some extent, and location of sound from the rear is not as strong as sound from the front.  In any event, I don’t really care for hearing music coming from behind and prefer that the recordings use the additional imaging capability to create a more naturally enveloping soundfield with the instruments still located in front.

The BACCH processing did create the sense of a more open and enveloping soundfield, but was not quite as amazing as others have claimed.  This could be just my personal reaction, but I know others who were also not that impressed.

With two properly placed speakers, sounds can appear to come from behind you if they are recorded out-of-phase with the rest of the music.  The effect is used relatively rarely, mostly on a few rock and ambient-music recordings.  I used it on my first Dr. Muso album, Music for Picking Your Nose.  Listen especially to the slide guitar solo on "Brilliant Sky" (which is an over-the-head circular-panned effect), but you may hear it on other tracks as well.

Sometimes out-of-phase sounds can sound like they're right next to your ear or even on the floor right in front of you.  Room reflections can interfere with hearing such sounds.  My dipole speakers minimize side reflections which could affect such sounds.

Listen to “When I need you “ by Leo Sayer for such an effect