sandyk (RIP Alex, 1939 - 2021)
Global Moderator 
Posts: 226
About Me: Retired ex Principal Telecommunications Technical Officer with 43 years at Telstra (Australia)
I am also a Moderator in Hi Fi Critic Forum
Electronics hobbyist for >65 years with DIY projects including Loudspeakers, Stereo FM tuner, S/W Regen Receiver, Superhet AM ,
Synchrodyne PLL AM tuner (Phase Lock Loop),Stereo Tape Deck, Amplifiers including I.C. types, Class A, Class AB 100W/Ch. (ETI5000) 240W/Ch. Mosfet (AEM6000) ,several DACs , numerous PSUs including VERY low noise (<4uV) types etc.for myself and friends
Audio Industry Affiliation: NIL
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Post by sandyk (RIP Alex, 1939 - 2021) on Aug 17, 2019 10:32:44 GMT 10
Most Electronic Engineers, and many others, claim that it is not possible to encode HEIGHT in a recording. The attached may be of interest when evaluating your own system.
Regards Alex
www.audiocheck.net/audiotests_ledr.php
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Post by Audiophile Neuroscience on Aug 17, 2019 17:35:14 GMT 10
Most Electronic Engineers, and many others, claim that it is not possible to encode HEIGHT in a recording. Hi Alex, as you know and as far as I understand, the idea is that only left/right discrimination in the horizontal plane is possible from most microphones pairs. As you move left/Right the amplitude response varies asymmetrically for each microphone, providing a localization cue. If you go up or down the amplitude response lessens with distance but does so symmetrically for each microphone. Same applies for depth. Supposedly then, you encode a L/R spatial localization information and everything else is a sense of closer or nearer due to sounding fainter, but not localized. Some argue then it is room interaction that provides these height cues and others a sense that High frequencies are perceived as higher and low frequencies perceived as lower. My supposition is that these cues must be encoded somewhere in the audio signal but I am not an audio engineer.
In humans it is the HRTF or shape of the ears and head affecting frequency response said to provide these height cues. Interestingly, people that have lost their ears (pinnae) like with burns patients do mostly adapt and once again perceive height localization IME.
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jkenny
Full Member
Posts: 83
About Me: Audio equipment designer forever in pursuit of more realistic & engaging music reproduction purely because of the extra enjoyment of music created by such reproduction.
http://Ciunas.biz
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Post by jkenny on Aug 19, 2019 22:44:17 GMT 10
Apart from the general spectral characteristics which seem to determine height location of sounds, my guess about how we perceive the Y dimension (height) has to do with the distortions introduced by the outer ear before the pressure wave hits our eardrum. The pinna & ear canal, not being symmetrical, means that the distortions introduced by these structures will be different depending on the direction that sounds hit these structures. My guess is that we have internally absorbed our own individual distortion mapping which helps us in locating sound direction. David Geisinger has done some interesting research into room/hall acoustics & also determined that in-ear microphone recordings produce a frighteningly realistic reproduction of the original sound - this is because the individual's outer ear distortions are incorporated in the recording. He has since introduced an equalisation system that allows each individual to map & set their individual distortions for more realistic sound - like an individual RIAA adjustment curve Have a look at "Accurate reproduction of non-individual binaural recordings without head tracking through individual headphone equalization" |
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Post by ROWUK on Aug 20, 2019 5:36:55 GMT 10
I think that they are right about not being able to encode it (except maybe for specific test tones) - we can learn to hear it however if the presentation is large enough. For the classically oriented audiophile, massed string sounds are most prominent reflecting from the ceiling. There is a figment of my imagination that lets me "hear" the reflections - even with mono recordings.
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