We had a rig in our original Music Technology room consisting of four Quad electrostatics (the original ones!) suspended about a metre and a half below the sloping wooden ceiling so they were above head height but angled so they were directed at a central head height point. The array worked very well at reproducing 1st order pieces on the horizontal but generated spurious 'up' (and 'down') images which we traced to reflections of the radiation from the back of the speakers from ceiling nd walls. I suspect Richard Furse will remember the surprise at the way images of sheep bleeting in "Don Quixote" seemed to go up and down when they should just have been horizontal. Don Quixcote was one of the first, possibly the very first, fully digital Ambisonic compositions, thanks to Sile O"Modhrain's Atar ST based software, SurroundSound *.
Dave *0'MODHRAIN, SILE 'Surroundsound, A B format Sounndfield processing program for the Composer's Desktop Project Soundfile system', ICMC Glasgow 1990 Proceedings, pp.121-123 On 2 July 2014 17:18, Martin Leese <martin.le...@stanfordalumni.org> wrote: > Sero wrote: > ... > > What is the best loudspeaker directivity (polar pattern) for an > ambisonics > > listening rig? > > > > I am very confused about this because I cannot find any reference on this > > on any pubblication or discussion on the net. > > The only work I know on this is a study by > Dermot Furlong using a simulator. He > discussed his work on the sursound list in > 1996; I have it preserved at: > http://www.ambisonia.com/Members/mleese/dermot/ > > Dermot considered only first-order Ambisonics. > Here is an extract: > > "I am very well > aware that ideal point source loudspeakers are usually > specified for ambisonic reconstruction, but their > directivities are not generally commented on, so > perhaps this is of interest. And yes I know that most > loudspeakers have frequency dependent directivities - > I was trying to address the more basic question as > to what was the effect of loudspeaker polar response > on reconstruction. What I found was that for > reasonably dead listening rooms, loudspeaker > directivity was not a major issue - as long as omni > radiation patterns were not used! However, for more > live listening spaces the effect of loudspeaker > directivity did play a significant role. Curiously perhaps, > in cases of more 'dead' listening rooms, dipole > loudspeaker directivities were found to lead to > reconstruction of Listener Preference Indices which was > as good as that of more directional loudspeaker polar > patterns. Furthermore, as the room was made > more lively, the reconstruction with dipole loudspeakers > was consistently and significantly better than > was the case with more directional loudspeakers! This > was a surprise to me, and I did look at the > implementation very closely to check everything was > working properly... but this remains a consistent > observation... for all reconstruction formats!" > > Regards, > Martin > -- > Martin J Leese > E-mail: martin.leese stanfordalumni.org > Web: http://members.tripod.com/martin_leese/ > _______________________________________________ > 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. > -- As of 1st October 2012, I have retired from the University. These are my own views and may or may not be shared by the University Dave Malham Honorary Fellow, Department of Music The University of York York YO10 5DD UK 'Ambisonics - Component Imaging for Audio' -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20140704/cd59314f/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.
