Bo, The point is that FOA never appealed to those elements of HRTFs in the 6K+ region (well, actually, much lower than that) - which is where pinnae cues are most important. That is, FOA simply 'neutralises' pinnae cues by homogenization Or, to put it another way, if you want pinnae cues (i.e. minimal wavefront error [I think Vanderkot and Lipshitz use KR error for this] at high frequencies) then you need high order, and the processing overhead climbs steeply with frequency. If you're prepared to settle for the rather neat solution that FOA homogenises pinnae cues in such a way as to not give spurious and erroneous cues, relying instead on Duplex components - it's fine up to a certain standard. But you won't have good control of height (pinnae again), though you can have good control of 'spaciousness' (via interaural cross correlation at LF, say, up to 1500Hz)
So High order might not be as valuable for sense of space as it is for precision localisation of sources. In respect of that precision - you're right that, whilst the optimum minimum audible angle (MAA) might be in the region of 1-2 degrees at 0 degree aximuth and elevation (Mills 1957), it very probably is more like 10 degrees at source angle =/- 90 degrees azimuth, and indeed, similar for +/- 90 elevation So, horses for courses; for most applications, FOA probably will be enough - especially as you say, if 'out-of-head' soundstage is a key ingredient; this is more to do with the reverberant field and its spatial qualities - and it may well be that that really doesn't need excruciatingly fine directional resolution to be perceptually effective. Same goes with the stable soundstage - the head tracking, combined with the out-of-head-reflected sound field will probably provide oodles of plausibility. Combine that with any visual input at all, as in VR - job done! Finally, as you say about adaptability - I mentioned earlier that one of the best ambisonic listeners I came across was Dave Malham - because of extended practice. - It's the same with sonar operators. So, for many VR operators, a training period can help operators learn to detect cues which, though 'fuzzy', are still sufficiently coherent to permit good performance. It just won't be instantly gratifying to the novice. But who cares about them? Dr. Peter Lennox Senior Fellow of the Higher Education Academy Senior Lecturer in Perception College of Arts University of Derby Tel: 01332 593155 ________________________________________ From: Sursound [[email protected]] On Behalf Of Bo-Erik Sandholm [[email protected]] Sent: 28 January 2016 21:12 To: sursound Subject: Re: [Sursound] Never do math in public, or my take on explaining B-format to binaural I do understand that HOA can represent resolution of directivity in the mathematic domain better than FOA. But I am starting to suspect we are overworking something when we are talking of order 8 to 15? Is it realistic to even think of measuring individual HRTF response with that angle resolution? And is it even neccessary when we know the adaptability of the auditory system? As stereo works good enough over 45 degrees with 2 speakers and correct psycho acoustic setup and a good recording are we not aiming for a overkill system? As a normal guy without training in listening for direction of sound sources I suspect I cannot really pinpoint many things in more than +-10 degrees without visual cues. I remember old discussion results about ideal number of loudspeakers for horizontal FOA replay being 6 speakers. My goal is to have a device that can play through headphones a stereo or FOA recording and give me a minimum experience of listening to a stereo system or FOA setup with out of head sound and a stable position of the soundstage. I am not certain this is relevant in this discussion thread as we probably have different views of the goals and the path to the goals. Bo-Erik On 28 Jan 2016 12:37, "Politis Archontis" <[email protected]> wrote: > Hi Fons, > > _______________________________________ > From: Sursound [[email protected]] on behalf of Fons > Adriaensen [[email protected]] > Sent: 27 January 2016 23:58 > To: [email protected] > Subject: Re: [Sursound] Never do math in public, or my take on explaining > B-format to binaural > > > plus independent decorators/reverberators per HOA channel, > > with different decays at different frequencies, for the > > late part. The late part filters require a further tuning > > stage though, to match the ‘sinc’ like binaural-coherence > > of left and right ear signals in diffuse sound. I have > > found that this matching improves significantly > > externalisation, and sounds more natural. > > I'd be much interested to learn more about that... > > Ciao, > > -- > FA > ________________________________________ > > sure I can expand on that, is it ok if I contact you or send you some text > off-list? > > I am wondering though, as I understood, you are interested in the case of > converting to binaural other multichannel formats with dynamic > head-tracking. In this case since you have discrete sources you are > binauralizaing, with some added room effect, is there a reason to go > through a second order ambisonic system, instead of using directly HRTFs > with some interpolation, plus a binaural late reverb? Don't you blur > significantly (well, up to a second-order blurring) the spatial resolution > of the HRTFs, considering again that we need orders of 8-15 for fullband > reconstruction of HRTFs at mid and high frequencies? > > Regards, > Archontis > _______________________________________________ > Sursound mailing list > [email protected] > https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, > edit account or options, view archives and so on. > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20160128/90b55ecf/attachment.html> _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on. The University of Derby has a published policy regarding email and reserves the right to monitor email traffic. 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