ericm@FtCollins.NCR.com (Eric.Mintz) (07/25/90)
Has anyone heard of bi-neural audio? One of the shows on NPR will have
a bi-neural broadcast some time this week (or early next week). The
broadcast will consist of classical and jazz. The DJ said that
headphones were necessary (I presume to get the full effect).
So, what is bi-neural audio??
--
Eric.Mintz@FtCollins.NCR.COM
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Eric Mintz, Software Development, NCR Microelectronics
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(303) 223-5100 ext 422 | little goof." Wally Cleavernelan@enuxha.eas.asu.edu (George Nelan) (07/26/90)
In article <ERICM.90Jul25114931@hendrix.FtCollins.NCR.com>, ericm@FtCollins.NCR.com (Eric.Mintz) writes: > > Has anyone heard of bi-neural audio? One of the shows on NPR will have Webster: binaural: adj 1: of, relating to, or used with two or both ears Better luck next time >:-= -- George Nelan, ERC 252, Arizona State University, Tempe, Arizona, USA, 85287 INET: nelan@enuxha.eas.asu.edu UUCP: ...{allegra,{ames,husc6,rutgers}!ncar}!noao!asuvax!nelan QOTD: <out to lunch>
tmn@gn.UUCP (07/26/90)
"Bi-Neural"? What an amazing name! Sounds like a stereo version of Pat Flanagan's Neurophone! But seriously, folks, do you mean "binaural"? If so, the technique is to record actuality with a 'dummy head' fitted with mics in the artificial ear canals. The two-channel signal is recorded normally and played back via headphones. There are advantages and disadvantages with the technique. The more accurately you model the dummy head the more individual-specific the effect is. A basic head will give a reasonable effect for anyone, while a highly-tuned head will give wonderful effects for some people and gross errors for others (generally the person whose head was modeled gets the best effect). The system is almost useless on loudspeakers, unless you face the speakers in to each other and sit between them (in which case you might as well have cans on). Binaural can, however, be transcoded into a speaker-based surround system, notably Ambisonics (a British-designed surround system based on Blumlein's original stereo research) with great success, the simplest method being to place the two channels at the east and west edges of the soundfield and then reduce the radius vector until best results are obtained. However this is not as accurate as a purpose-build transcoder. The resulting Ambisonic B-format signal can then be UHJ 2-channel encoded and treated as stereo if desired. The main problems encountered in dummy head work is that good modeling requires some special components: some researchers believe that internal head density is important and have simulated this with fluid bags inside the dummy head. Ear canal modeling has always been important and it is pinna differences that are generally regarded as making the system person-specific (see above). Another consideration is that the signal actually passes through the ear canal twice: once through the artificial one and once through your own (if you are wearing cans). This can be compensated for in binaural-to-ambisonic transcoding but in a traditional headphone-listening environment an equalizer is required along with a phase-compensation network which can adjust phase with frequency. The curves for both of these are available in the literature and notably in the Sony and Matsushita patents of the mid-Seventies. Interestingly, neither company has exploited these discoveries commercially. The best commercial exploitation of binaural techniques to date was that by Hugo Zuccarelli, an Argentinian based temporarily in Europe during the early Eighties. Zuccarelli called his system "Holophony" and was not prepared to discuss what went into the system in detail: what he did say is generally regarded as meaningless pseudoscience designed to cover up what he had actually achieved to avoid it being ripped off. However when he split up with his former collaborators and, after extensive legal difficulties moved to LA, his former partners confirmed the view that Zuccarelli's system was based on fully-implementing head modeling, phase and EQ compensation, internal densities, etc etc as described above. It has been suggested that another reason Zuccarelli was never forthcoming on what was _really_ involved in his system was that he may have infringed the Sony and Matsushita patents inadvertently in the course of his own research (it is not believed that he ripped them off). For some reason every project that he was involved in became the subject of litigation, and ultimately the system faded from view. It was, however, the best binaural system to have been used commercially to date. There are some distinct possibilities in combining binaural and ambisonics, as binaural is particularly good on nearby (<1m) moving sources while the ambisonic Soundfield mic tends to de-localize when close to the capsules. Ambisonics, on the other hand, can be used with conventional multitrack and mixdown systems via Ambisonic panpots and other devices which can be computer-controlled and simulated (viz the work done by Dave Malham at the University of York, UK) while binaural requires actuality recording and is difficult to synthesize or use in a multitrack environment (binaurally recording the sound of speakers in a room is generally disastrous: this is better achieved with a Soundfield mic). -Richard Elen at The Music Network (tmn@gn.UUCP)
george@wind55.seri.gov (George Scott) (07/27/90)
nelan@enuxha.eas.asu.edu (George Nelan) writes: >In article <lins.NCR.com>, ericm@FtCollins.NCR.com (Eric.Mintz) writes: >> >> Has anyone heard of bi-neural audio? One of the shows on NPR will have >Webster: binaural: adj 1: of, relating to, or used with two or both ears >Better luck next time >:-= But you could have told him what it was. Binaural recordings are made with two microphones placed in the same relationship to each other as the two human ears are to each other. (There may be some attempt to model the acoustics of the ear canal,... Some recordings are made with an actual model of a head with mikes in each ear.) Disclaimer: Anybody know more about this than me? Probably. Why don't you tell us more? -- ------------------------------------------------------------------------------- George N. Scott EMAIL: george@wind55.seri.gov Wind Research Branch. VOICE: 303-231-7667 Solar Energy Research Institute 1617 Cole Blvd., Golden, CO 80401-3393
stank@anvil.WV.TEK.COM (Stan Kalinowski) (07/27/90)
In article <ERICM.90Jul25114931@hendrix.FtCollins.NCR.com>, ericm@FtCollins.NCR.com (Eric.Mintz) writes: > > Has anyone heard of bi-neural audio? One of the shows on NPR will have I believe the correct term is binaural. In this context it refers to a method of recording that involves stereo microphones placed in the ear positions in a mockup of a human head. The theory is that the recording contains all spacial auditory information that the ears would gather if they were at the original performance. It is necessary to use headphones on playback so that there is no "crosstalk" between left and right ears. (i.e. the sound field is reproduced the same way as it was recorded.) In my opinion, the only flaw in this concept is that it cannot reproduce the effect of moving one's head to gain more perspective on the sounds directional characteristics. Similar head movements are used by humans and some animals to help visually judge distance. Despite the limitations of the binaural recording, I think the NPR broadcasts are a wonderful way to allow a larger group of people experience this unique recording technique. It might be interesting to see if keeping your head very still and your eyes closed enhances the illusion of being there. Of course, you then run the risk of becoming bored and falling asleep. :-) stank US Mail: Stan Kalinowski, Tektronix, Inc., Interactive Technologies Division PO Box 1000, MS 60-850, Wilsonville OR 97070 Phone:(503)-685-2458 e-mail: {ucbvax,decvax,allegra,uw-beaver}!tektronix!orca!stank or stank@orca.WV.TEK.COM