Please don't be so dismissive. It is possible for a sound reach your ears from behind without the original source such as speakers being behind you, if the sound in confined to a beam and bounced/reflected off a wall behind you.
This sometimes happens naturally outside, when a sound reflects off a mountain or large building. You may only hear the reflection if the sound's path from the source to your ear is blocked by a building, a hill or so on.
While most sound bars use a variety of methods to simulate surround sound, Yamaha's YSPs produce sound beams that bounce off side and back walls of a room and can make sound reach your ears from behind. You do need walls to make YSPs work, of course.
Yamaha licenses the technology from Cambridge Mechatronics Ltd (CML, originally called 1... Ltd). The technique involves having one or more rows of transducers (small loudspeakers -- Yamaha calls them beam drivers). The sound beam can then be directed at an angle. This is done by delaying the signal from one side of the row(s) to the other, to build up a wave front travelling in the desired direction. By 'curving' the delays and wave fronts, it's even possible to focus the beam.
Here's Yamaha's diagram of how the beam is built up and directed:
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With a large number of transducers you can get a strong beam effect, but it can become very expensive. Pioneer was the first to market with a product
(Pioneer PDSP-1) which had 254 transducers, but it cost about $40K.
I think Yamaha's YSPs vary from about 16 to 40 transducers and are clearly much more affordable. Although many people may prefer the sound of a good conventional surround sound system, most people hearing a good digital sound projector, such as Yamaha's YSP-4100, are surprised and impressed with the surround sound effect from a single unit in front of them, (though they are expensive and you'll most probably need a subwoofer). If you don't believe me look at the reviews of the YSP-4100.
Yamaha's diagram showing the surround-sound beams:
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For a better explanation and another diagram go to CML's
'How it works' web page.
Some TVs manufacturers (eg, Mitsubishi, Grundig and Beko) are also using this technology.