Hello Everyone, First, many thanks for responses and insights to my recent post (Testing left, center, right...).
I look forward to trying Fon's suggestion--I'm always game for a listening experiment as long as high SPLs aren't involved. Regarding Dave's post and the following link: **This may be the answer to the lack of a feeling of moving... http://www.kickstarter.com/projects/1944625487/omni-move-naturally-in-your-favorite-game?ref=category Dave** Maybe Ambisonics combined with Wii will start a trend in surround entertainment? I recently joined Kickstarter because of numerous art and science projects I have in mind. One design, near completion, is a unique self-calibrating audiometer for use in developing countries (such as the USA). Seriously, people in the UK and US can submit proposals to Kickstarter and have chance for *free* funding. For those unfamiliar, it's worth a look (by the way, it was a Sursound reader/contributor who suggested Kickstarter to me--thanks!). Regarding Eero's comment, **I guess the other option to extract the center speaker information from two channel stereo is a Dolby Surround decoder, which you know much better than any of us, Eric.** For those who are regular readers, you probably know there are a number of Eric's on the list. I generally sign off as Eric C. so as not to embarrass the wiser and brighter Erics. One of the *other* Erics is an expert of Dolby. I don't know a whole heck of a lot about Dolby, but I did create a pseudo decoder for AC3 that used analog filters to get a 90 degree phase shift. For a single frequency, shifting 90 degrees is trivial. But for a complex tone, shifting the fundamental (for example) 90 degrees won't result in ALL of the composite frequencies being shifted 90 degrees. The filter was akin to a *Hilbert transformer* in that it is frequency-independent across the audio frequencies (or at least 50 Hz - 10 kHz based on Bode and phase plots). I've tried to explain this to those who are not mathematically inclined, but who have some familiarity with Fourier transforms (even if it's on a non-mathematical basis). You see, Hilbert transform is something of a *buzz word* among cochlear implant research, but not too many know its function aside from an aid in extracting a speech signal's envelope. If we perform a Fourier expansion on a square wave (Wikipedia good source of demo)--you'll see coefficients such as 1/3, 1/6, etc. ahead of sin(...). Moving all of the sines *forward* or *backward* by 90 degrees is (I think) equivalent to a Hilbert transform and, consequently, a way of shifting a complex wav by 90 degrees. Moving sin forward 90 degrees is -cos, moving backwards is + cos. This is obviously bit more complex than a 180 degree inversion. Why 90 degrees? I dunno, just seems cool to try and listen to (remembering, of course, there also has to be a reference signal). Also a part of decoding. Remember that I'm NOT the smart Eric, so I can't give better explanations. Best to all, Eric C. -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20130622/37175464/attachment.html> _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
