Hi Fons, these are great points you raise here!
On 27 Jan 2016, at 00:13, Fons Adriaensen <f...@linuxaudio.org<mailto:f...@linuxaudio.org>> wrote: I've been reading this thread with much interest, as it is exactly about the topic I've been working on for the last two months. * Most HRIR sets have an LF response that is almost certainly not correct. Up to a few hundred Hz it should be flat. One essential step in the preparation is to fix this. How this is done best depends on the particular data set. If this is done correctly you can trim the IRs to a few ms without any adverse effect. Something that has worked well for me is to replace the (unmeasurable) low frequency HRTF with the response of a spherical head model, including the phase response, normalised to match the rest of the measured HRTF. One can go more exact and find a “personalised” sphere radius, with a more realistic ‘off-horizontal’ position of the two receivers (ears) on the sphere. This approach has been used too to fit a sphere on a quick Kinect head scan, for personalised ITD estimation, with good results: "Hannes Gamper, Mark R. P. Thomas, and Ivan J. Tashev, Anthropometric Parameterisation of a Spherical Scatterer ITD Model with Arbitrary Ear Angles<http://research.microsoft.com/apps/pubs/default.aspx?id=258403>, in Proc. IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA)” * All content derived from non-surround sources (e.g. plain stereo or 5.1) requires some 'room sound' to work well. Externalisation seems to depend on having early reflections from different directions (which would allow the brain to compare their spectra). Generating such room sound can be done in the AMB domain. What exactly is required and how to do that efficiently is my current research problem. Again something that has worked well for me is to use a few HOA-encoded point sources as early-reflections, 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. Regards, Archontis -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20160127/c68dc5e1/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.
