height information in reproduced sound stage (Off Topic)

by kurt s , Thursday, March 29, 2007, 23:22 (6238 days ago) @ Rudolf150

"Is it possible to reproduce height information from a stereo setup?"

I say the answer is yes, but poorly. To get real height information the sound source must provide clues to the ears that the ear needs to interpret movement in height. Those clues are subtle shifts in timing and frequency response in both channels simultaneously that make the brain interpret that sound as moving up or down as opposed to left and right.

The outer ear has a shape around it that forms a different frequency response in the top position compared to the forward position and compared to the rear position. If all is done well, then the brain might interpret the sound to be above you if with the proper timing information as well as your ear's frequency response information. How do you put such information into a pair of speakers? You must encode it in there. How are recordings done? Almost all without such encoding. So actually, sounds that do appear to move up are the result usually of an accidental effect in the recording.

Mikes do have polarized frequency responses. They change with angles reaching them. If mike(s) are made and positioned to slightly encode the sound an ear would hear with such movement in height, to a rather crude fidelity to that effect, then it can project an illusion of height information in the playback, just like stereo is mainly a left-right illusion.

So again the answer I have is: Yes, some crude form of height info can be in there, but no, it is not natural nor intentional in two-channel, two-point-source recordings. And yes, you do hear it sometimes. And some speakers are much more adept at presenting such slight information clues. The best speaker I ever owned that did this effect was my Avalon Eclipses when I had those. Then I swore all recordings had height. But, alas, that was mostly illusion, and not "real". Does "sort of" make a good answer here?

Kurt

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