Now there's a highly technical term you don't hear often; hoobajoobs. LOL!
If I have the correct "hoobjoob" picked out, It is, indeed, a wireless transmitter for the wireless headphones resting on the cable box. Specifically it's a Sony MDR-IF5100
with "virtual" Dolby Digital surround, and DTS "virtual" 5.1, both of which are VIRTUALLY useless. When you use them in the alleged surround modes, at first, it kinda sounds like you fell into a metal garbage can. After an hour or two, that begins to sounds fairly decent, but by that time the movie is VIRTUALLY over. They cost an arm, a leg, and my first born (though I didn't pay anywhere near what they want for them on the Sony web site), and they aren't the REALLY expensive Sony MDR-DS8000
That's the down side.
The upside is they sound very good, and, being wireless, they allow some reasonable movement as long as you are in line of sight of the infrared transmitter. I've had to deal with wires all my life, and have come to loathe them. They drive me nuts, so wireless is always attractive to me.
I would recommend wireless headphones (but be selective, not all of them are good), but don't waste the money on the virtual surround stuff.