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Is it possible with standard stereo to hear sounds behind you?

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You know something is behind you because of wave arrival timing and spectrum balance cues. Left to right stereo isn't that hard, its basically

slight volume/spectrum differences between what each ear hears. Front to back is much harder, room acoustics, speaker dispersion and positioning

have to be very good for the cues not to be altered and indistinct. To hear something behind you sounds like a UFO sighting unless you have a multi-track recording...

stereo  has no 3rd track for a speaker behind you to present the needed audio cues.




Audio system

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If your two-channel stereo system is set up optimally, with the listening room having ideal size, shape, and symmetry, and the speakers delivering to your two ears the ideal balance between direct and indirect (uncorrelated) sound that is correct spectrally and temporally, your ear/brain will be able to localize an astonishing variety of sonic events, including right-sized instruments, percussion, voices, and ambient cues in not only the front hemisphere, but also to the sides, and occasionally in the back.  The reproduced signals from recordings are extremely fragile however, and most two-channel stereo systems struggle to achieve this ideal, typically requiring extensive room treatment as a fundamental which most people neglect to implement, much less understand.


After much effort, my system (see photo) has achieved decent optimization, to a point where I routinely hear instruments "float" in high resolution inside a broad, deep, and vast soundstage in a gigantic virtual "cube" (or "sphere", depending on your preferred perspective) whose dimensions well exceed the physical boundaries of the perimeter defined by the borders of my two L and R speakers, and are proportioned evenly along the X, Y, and Z (width, height, and depth) - something I have not yet heard any other system.


The components in my system are listed under the blue tab "Audio System" (after clicking through my ID name); alternatively, here's the URL link:



Modern recordings increasingly frequently incorporate sound effects synthesized by the pre-programmed tweaking of frequency amplitude and phase to achieve localization which "pop" out or "ghost" out to the sides like an unbound floating apparition, right from the mixing board.  Apart from the Q-Sound treatment of albums like "Amused To Death" by Roger Waters, one pop recording track which vividly demonstrate this a 360-degree wrap around effect is the song "Hotline Bling" by Drake.


About halfway into the song, there is a passage which project floating sonic objects swirling around the listener's head in a large donut-shaped cloud.  During this event, it's easy to turn one's head to both the left and right, to clearly hear the sound floating BEHIND the listening position.


Give this a try, and let me know what you hear!  :-) 

IMG_5758 small.jpg

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BTW find the original PCM, non-MQA version of "Hotline Bling" to playback, as I suspect that MQA imparts a coloration which is not faithful to the original recording by injecting signals which reduce inter-aural crosstalk, similar to Bob Carver's Sonic Hologram (from the 1980s) to produce a more spacious sound which better delineates the images inside the soundstage as well as unbound it from the small "between the speakers only" sound.  The way in which this is done is during the MQA encoding process, where the "juiciest" midrange portion of frequency spectrum is inverted and injected into the opposite channel and delayed slightly in a manner corresponding to the time it takes for sound to travel between the distance of the eardrums over the front face.  Anyway, this discussion is probably done in private, as MQA fans have a nasty way of discouraging me from going any further with this line of reasoning.  I would love to see a website which specializes in objective measurements test my hypothesis, but I think it would take some time before someone with access to an MQA encoder has the chance to produce just such a test disc which will demonstrate what I think may be happening.


The bottom line is that if "Hotline Bling" was originally recorded with a particular phase-and-frequency shift synthesis/processor, it's best to hear it in its original file, instead of embellishing it with even more sauce, ala MQA. 


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  • 4 weeks later...

Montrose - Space Station #5

Near the end, just before getting to the strong standard swirl-around-your-head phase effect, there is a wave that travels back and forth behind the listeners neck..


Pretty much that entire album is a true rock classic...


For more natural stuff, +1 on the Chesky CD's


A high priority for my preferences is a large deep sound-stage, so I built some columns to help inter-aural crosstalk cancellation by delaying some of the opposite side speaker arrival. I think this helps stabilize my system's performance for this attribute - and when I make some changes, Space Station #5 provides a good reference.

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