I have skimmed through it too. Nothing on curvature, but it’s very interesting non the less. It needs a thorough read through
One of the many encoding and decoding solutions at grabbed my attention (it’s very comprehensive) is: '‘D’ Channel (as in WXYZD) The ‘D’ channel will encode as a normalized distance which can as one example be recovered as value of 0 (being in the head at the origin), 0.25 being exactly in the near-field, and up to 1 for a source rendered fully in the far-field. This encoding can be achieved by using an absolute value reference such as 0 dBFS or by relative magnitude and/or phase vs one or more of the other channels such as the “W” channel. Any actual distance attenuation resulting from being beyond the far-field is handled by the B-Format part of the mix as it would in legacy solutions By treating distance m this way, the B-Format channels are functionally backwards compatible with normal decoders by dropping the D channel(s), resulting in a distance of 1 or “far-field” being assumed. One method of encoding the D channel is to use relative magnitude of the W channel at each frequency. If the D channel's magnitude at a particular frequency is exactly the same as the magnitude as the W channel at that frequency, then the effective distance at that frequency is 1 or “far-field.” If the D channel's magnitude at a particular frequency is 0, then the effective distance at that frequency is 0, which corresponds to the middle of the listener's head. In another example, if the D channel's magnitude at a particular frequency is 0.25 of the W channel's magnitude at that frequency, then the effective distance is 0.25 or “near-field.” The same idea can be used to encode the D channel using relative power of the W channel at each frequency.' It’s a DTS patent application too, so it also covers loads of options for matrix-ing. Happy Monday Steve > On 29 Jan 2018, at 10:41, Augustine Leudar <augustineleu...@gmail.com> wrote: > > Thanks for the list Markus, > I read the conclusions and abstracts for these papers and skimmed through > them - I am also quite busy ! However none of them seem to investigate or > suggest that the curvature of the wavefront and this curvatures interaction > with pinna folds is a potential distance and size cue in the nearfiled. I > did find this though which mentions it but doesnt really investigate (or > reference a source unfortunately) : > > https://pdfs.semanticscholar.org/0664/8964b53ac8f812b0068088caa4838c3ba7ce.pdf > > On 24 January 2018 at 14:35, Markus Noisternig (IRCAM) < > markus.noister...@ircam.fr> wrote: > >> Dear All, >> >> Here are some references: >> >> Brungart and Rabinowitz [1] showed that HRTF vary significantly for >> sources in the proximity region (i.e. at distances less than 1m from the >> head). >> Lentz et al. [2] perceptually evaluated measured HRTFs at different >> distances from the head, showing limits of noticeable differences between >> near-field and far-field HRTFs. >> Romblom and Cook [3] proposed near-field compensation filters. >> Duraiswami et al. [4], Zhang et al. [5], and Pollow et al. [6] compute >> HRTFs for arbitrary field points using spherical harmonics decomposition >> (as an extension of the work of Evans et al. [7]). >> Duda and Martens [8] evaluated simulation results on a spherical head model >> >> Have fun reading! >> >> Very best, >> >> Markus >> >> [1] D.S.Brungart,W.M.Rabinowitz:Auditorylocalizationof nearby sources. >> head-related transfer functions. J. Acoust. Soc. Am. 106 (1999) 1465–1479. >> [2] T. Lentz, I. Assenmacher, M. Vorländer, T. Kuhlen: Precise >> near-to-head acoustics with binaural synthesis. Journal of Virtual Reality >> and Broadcasting 3 (2006). >> [3] D. Romblom, B. Cook: Near-field compensation for hrtf processing. >> 125th Conv. Audio Eng. Soc., San Francisco, USA, 2008, no. 7611. >> [4 ]R. Duraiswami, D. N. Zotkin, N. A. Gumerov: Interpola- tion and range >> extrapolation of HRTFs. IEEE ICASSP, Montreal, Canada, 2004, 45–48. >> [5] W. Zhang, T. D. Abhayapala, R. A. Kennedy, R. Du- raiswami: Modal >> expansion of HRTFs: Continuous repre- sentation in frequency-range-angle. >> ICASSP, Los Alami- tos, USA: IEEE Computer Society, 2009, 285–288. >> [6] Pollow, M., Nguyen, K.-V., Warusfel, O., Carpentier, T., >> Müller-Trapet, M., Vorländer, M., and Noisternig, M. (2012). “Calculation >> of Head-Related Transfer Functions for Arbitrary Field Points Using >> Spherical Harmonics Decomposition,” Acta Acust United Ac, 98, 72–82. >> doi:10.3813/AAA.918493 >> [7] M. J. Evans, J. A. S. Angus, A. I. Tew: Analyzing head- related >> transfer function measurements using surface spher- ical harmonics. J. >> Acoust. Soc. Am. 104 (1998) 2400– 2411 >> [8] R. O. Duda, W. L. Martens: Range dependence of the re- sponse of a >> spherical head model. J. Acoust. Soc. Am. 104 (1998) 3048–3058. >> >> >>> On 24 Jan 2018, at 15:01, John Merchant <john.merch...@mtsu.edu> wrote: >>> >>> Tom Smurdon and Peter Stirling of Oculus presented research on >> near-field HRTF for VR at last fall's OC4. The video of that talk is >> available here: >>> https://www.youtube.com/watch?v=l7mhXRB9PA4 >>> >>> ________________________________________ >>> From: Sursound <sursound-boun...@music.vt.edu> on behalf of >> st...@mail.telepac.pt <st...@mail.telepac.pt> >>> Sent: Tuesday, January 23, 2018 8:12 PM >>> To: Surround Sound discussion group >>> Subject: Re: [Sursound] A submittal for a patent on Ambisonics? >>> >>> Citando Augustine Leudar <augustineleu...@gmail.com>: >>> >>>> Hi Jack, >>>> >>>> Aside from ILDs, ITDs, I also wondered if the pinna was able to >> distinguish >>>> >>>> very close sound sources due to the fact the wavefront would be much >> more >>>> >>>> curved almost spherical to the degree that it would be different >> pressure >>>> >>>> present at different folds of the pinna (ie very close up sound slike >> a >>>> >>>> mosquito) . I dont think theres been much done on that... >>> >>> Hi Augustine, >>> >>> I think "there has been done quite a lot on that"... 😉 >>> >>> (Reproduction of near-field audio sources) >>> >>> Beside of spherical waves (and their consequences) we should not >>> overlook that any high-frequency emitting (annoying) mosquito next to >>> your left ear would be heard much softer at your right ear, the head >>> shadow being even more relevant at close distances. >>> >>> BR >>> >>> Stefan >>> >>> P.S.: It is important to know about the "depth" of a mosquito audio >>> object relative to your head, both in VR and in real life... >>> >>>> On 23 January 2018 at 11:58, jack reynolds <jackreynolds...@gmail.com> >>>> >>>> wrote: >>>> >>>>> It looks like a method for binaural rendering with multiple distance >> HRTFs. >>>>> >>>>> >>>>> >>>>> Ambisonics could be one of the inputs, but it seems to be aimed more at >>>>> >>>>> object based virtual reality, where the listener is more likely to come >>>>> >>>>> very close to an audio source. >>>>> >>>>> >>>>> >>>>> Most HRTFs are currently measured at 1m distance, so any objects closer >>>>> >>>>> than 1m are not currently rendered correctly. >>>>> >>>>> >>>>> >>>>> Far field HRTFs are closer to plane waves, whereas close up audio >> objects >>>>> >>>>> emit more spherical waves, creating greater differences in interaural >> time >>>>> >>>>> difference (ITD). >>>>> >>>>> >>>>> >>>>> Jack >>>>> >>>>> >>>>> >>>>> On 23 January 2018 at 11:18, Bearcat Şándor <bearcatsan...@gmail.com> >>>>> >>>>> wrote: >>>>> >>>>> >>>>> >>>>> I don't know a lot about patent law, but is this an attempt to tie up >> our >>>>> >>>>> beloved Ambisonics? >>>>> >>>>> >>>>> >>>>> http://www.freepatentsonline.com/y2017/0366912.html >>>>> >>>>> >>>>> >>>>> .... >>> -------------- next part -------------- >>> An HTML attachment was scrubbed... >>> URL: <https://mail.music.vt.edu/mailman/private/sursound/ >> attachments/20180124/16ff3135/attachment.html> >>> _______________________________________________ >>> Sursound mailing list >>> Sursound@music.vt.edu >>> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, >> edit account or options, view archives and so on. >>> _______________________________________________ >>> Sursound mailing list >>> Sursound@music.vt.edu >>> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, >> edit account or options, view archives and so on. >> >> _______________________________________________ >> Sursound mailing list >> Sursound@music.vt.edu >> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, >> edit account or options, view archives and so on. >> > > > > -- > Dr. Augustine Leudar > Artistic Director Magik Door LTD > Company Number : NI635217 > Registered 63 Ballycoan rd, > Belfast BT88LL > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20180129/25749dd6/attachment.html> > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > 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/20180129/a2c32aae/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
