Hi Michael, Thanks for the note. At least I got as far as 2*pi radians / 5 = 105 degrees. Oops, I meant 72--the 105 degrees (Fahrenheit) is today's high temperature for Phoenix (and I'm more than ready for summer here to be over!!). Seriously, the math for speaker feeds from B-formatted material isn't at all daunting, though I can't say the same for A- to B-format conversions. I just wasn't sure whether even numbers and symmetry have been used as a matter of convenience, or whether each speaker requires a directly-opposing "complement" speaker for best wave field reconstruction. I have six speakers, but one is to be used independently of the others and may not be arranged in accordance with the other five speakers. The remaining five (should I go this route) will have equal spacing among them. Some of the VST plug-ins provide B-format-to-5.1 surround conversion, and a 5.1 layout (minus the 0.1) could work for me, too. My arrangement doesn't require equal loudspeaker spacing. Speaking of 5.1... I believe the Waves IRs for surround have been converted from B-formatted IRs to a proprietary format (?) for 5.1 application; i.e., I don't think they have B-formatted wav files that users can apply to speaker arrangements of their choice. I know a lot of the IRs on Acoustics.net (Waves library of IRs) were recorded with a Soundfield mic along with Prof. Angelo Farina's expertise, but the Waves library and IR-360 surround convolution software is geared more for home and theatre surround systems. Am I correct in saying this? I just downloaded a trial version of Waves IR-360 to see what their VSTs offer. Of course, the Ambisonic (B-format) IRs provided free-of-charge on OpenAirLib.net and Space-Net.org provide a lot of material for auralization, and I'm grateful to everyone who has provided recorded material as well as food for thought. Kind regards, Eric
________________________________ From: Michael Chapman <s...@mchapman.com> To: Eric Carmichel <e...@elcaudio.com>; Surround Sound discussion group <sursound@music.vt.edu> Sent: Wednesday, October 3, 2012 12:24 PM Subject: Re: [Sursound] Hybrid Hi-Fi (HyFi?), IRs, etc. > Greetings to All, > I have been reviewing the literature on Auralization in attempts to create > viable stimuli for research. Everybody here has been great. I do have > another question/comment regarding loudspeaker placement. > In nearly all Ambisonic setups, the listener's head lies on a line > connecting two or more speakers. This includes the 4-speaker cube > arrangement. I've noted that having two speakers immediately to the left > and right of the head creates an image that's similar to headphone > listening; in other words, it's akin to lateralization versus localization > effects. Is there any reason not to use an odd number of speakers arranged > in such a way that no two speakers form an imaginary line passing through > the listener's head? You mean you want two speakers to form a real line through ... ... ;-)> But, seriously, I seem to remember matrices for pentagons (?Richard Furse's site). No reason why you shouldnt sit down and work out equations for non-even numbers. In practice as the minimum speaker requirement (pantophony) for 1st, 2nd, 3rd, 4th-order is 4, 6, 8, 10, I don't think non-even has been used much ... > I am considering building a hybrid system based on > Ambisonics and Ambiophonics, and was considering a pentagonal loudspeaker > arrangement. The "Ambiophonic" component would be using dividers (gobos or > flats, as they're called) between speakers so as to reduce early > reflections in an otherwise "standard" living room space. From what I've > read about Ambiophonics, it's an extension of transaural stereo techniques > (e.g. William Gardner's doctoral > thesis) with the addition of a partition. It seems that the advantages > provided by the partition (or partitions in my case) would apply to > Ambisonics. Please bear in mind that I am designing a system for > single-listener research, so the obvious disadvantages of dividers (i.e. > space hogs) isn't an issue. Has anyone had experience using dividers? > I've also been creating research stimuli using avatars (for lipreading), > AT&T Natural Voice text-to-speech (ATT Labs makes high res voices) > software for creating sentences, and IRs recorded with a SoundField mic. > Daniel Courville's website and Bruce Wiggins WigWare are fantastic > resources for any of us attempting sound design via Ambisonics. I also > have a licensed (meaning paid-for) version of Harpex, and this is highly > recommended for those who can afford it. One of my favorite post > production DAWs is Sony Sound Forge 10. I'm often having to convert > numbers of channels (e.g., four B-format channels to 8 processed > channels), and this is very easy to do with Sound Forge. I also use > digidesign Pro Tools and Steinberg Nuendo, but neither of these is as easy > to use as Sound Forge. > For the home brew crowd out there, I'll probably upload my plans for a > multi-channel preamp based on Burr Brown chips. The impetus for building > such a device (versus buying a ready-made surround sound > controller/preamp) is that I can use software to control the gain on the > Burr Brown chips (a rotary controlled encoder is used for conventional > volume control). I'm devising experiments where the signal-to-noise ratio > has to vary depending on a subject's response (e.g., two "misses" in a row > means increase the SNR). The software controller does this automatically, > and a MIDI track on a DAW can be used to track the changes. Just passing > this along for other researchers... > Disclaimer: Suggestions, questions, and ideas presented herein are in no > way a reflection of my cat, who is far wiser than yours truly. > Eric > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121003/b2a838f7/attachment.html> > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121003/1d0f6417/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
