Re: [Sursound] Of stereo miking, Fourier analysis, and Ambisonics
I do not understand the last bit of this message below at all. There is no such thing as a signal that is limited in bandwidth and in time--not if limited means actually 0 outside a finite interval in both cases. This is a basic result of Fourier analysis. This kind of signal does not exist, not mathematically and of course not physically either. Robert On Fri, 28 Jun 2013, Fons Adriaensen wrote: On Thu, Jun 27, 2013 at 04:33:46PM -0700, Eric Carmichel wrote: I have to agree with Joern that the example miking demonstration isn?t all that fair, and for another reason: How much low-frequency energy can a 2-inch speaker provide? I don't know what kind of signal was used for this test, but what we hear as a 'click' doesn't have to be fully 'broadband'. A short burst of e.g. octave band noise (or almost any signal) will sound as a click. but I?ll have to state that I don?t believe the ear works exactly as math would predict. Let me explain... Well, math doesn't try to predict how our ears work... We can use some mathematical model to try an understand that, but that model wouldn't be the canonical Fourier tranform defining the relation between a pure time domain description of a signal and a pure frequency domain one. Clearly our perception of sound is a mix of those two domains. The fuzzy border between the two seems to be at around 20 Hz - anything that repeats at a lower frequency will have more chance to be perceived as sequence of discrete events, if it repeats faster we will hear it as a signal having some frequency. A short time FT is a more appropriate model in that case. We can also assume that the signal we are using is bandlimited, and thus think in terms of sampled signals and use the discrete FT. A DFT of lenght K samples will provide a spectrum consisting of K/2 complex values [*]. The classical way to interpret this, found in all textbooks, is to assume that the signal is cyclic with a period of K samples, its spectrum will be discrete and consist of frequencies that correspond exactly to the 'bins' of the DFT. But what if we don't assume that the signal is cyclic, but a single event preceded and followed by silence ? What does the DFT output mean in that case ? That is actually quite simple: the K/2 values are samples of the continuous spectrum. And they are all that is needed in order to know that spectrum completely, just as the K samples of the signal are all that is needed to reconstruct the continuous signal. Instead of the required condition for the latter - the signal being limited in bandwidth - the condition for the discrete spectrum being a complete (i.e. invertible) description of the signal is that the signal is limited in time. This is just the dual of the Nyquist sampling theorem. The factor of 2 that appears only in one case is because we are using real-valued signals but complex-valued spectra. What this shows is that you don't need any infinities to exactly describe a signal that is limited both in bandwidth and time. Ciao, [*] More correctly, K/2-1 complex ones and two real-valued ones at 0Hz and Fs/2. -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Giving Precedence to Ambisonics
On 29 June 2013 13:21, Jörn Nettingsmeier wrote: Jörn You have just proved conclusively that there are things which are truly high fidelity without having anything directly to do with recording. The sonic image generated in my imagination by what you wrote of your encounter with Mike was totally realistic, right down to the need for asbestos underwear... Dave :-) > > the pleasure of discussing miking techniques with mr. williams :) > i met mike at the last tonmeistertagung in köln, where my very unfortunate > job was to tell him that we couldn't re-rig the speakers in precisely the > 3d arrangement he wanted, just for his talk, so i went ahead and matrixed > it onto an auro-3d setup. needless to say, he wasn't quite buying this idea > (it was more a "show or no show" kind of decision), and i got a healthy > dose of his microphone philosophy. while i wasn't convinced by everything > he put forward, it was quite interesting nonetheless. > > the funniest aspect of that situation was that i found myself defending > auro-3d (because that's what we had designed into that room) :-D > > i briefly mentioned that, if i had had my way, there would have been a HOA > hemisphere in that room, and boy did i long for my asbestos underwear... > > -- > Jörn Nettingsmeier > Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 > > Meister für Veranstaltungstechnik (Bühne/Studio) > Tonmeister VDT > > http://stackingdwarves.net > > __**_ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/**mailman/listinfo/sursound<https://mail.music.vt.edu/mailman/listinfo/sursound> > -- -- 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/20130629/6bfee65d/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
[Sursound] Mono Mia!
Hello Goran, I enjoyed your post (re Sursound Digest Vol 59 Issue 27). I'm a big fan of Ambisonics, as I'm sure nearly all readers here are. But Ambisonics doesn't cover all bases, and (in my opinion) neither can any single miking technique. What we often overlook is the quality or timbre a mic brings to the recording, and how this affects the artistic aspect of the performance. What you said about mics and speakers is what I try to convey to students: A system that is only as good as it's weakest component. But there can also be unexpected synergy across components that yield outstanding results. I'd much rather listen to a high-quality monaural recording that a marginal stereo or surround recording--who wouldn't? When I attend a concert or event, I don't get goosebumps because I can localize a sound or notice the absence of combing effects. The rush comes from the art, and the live experience has many dimensions. I'll confess that I don't listen to a lot of classical or symphony music. I've seen Itzhak Perlman, Christopher Parkening, Kodo Drummers of Japan, Brian Setzer Orchestra (swing jazz plus Stray Cats), Joe Jackson, Pilobolus Dance Theatre, Moscow Symphony Orchestra, Talking Heads, and a lot of diverse performances at Centennial Hall in Tucson, AZ. Nothing compares to live performances, but that doesn't make listening at home any less enjoyable. What can ruin any experience is simply bad sound--mono, 10.2 surround, Ambisonics, whatever. In some instances (such as seeing Itzhak Perlman), I don't believe I'd want a live, surround recording because of the number of squealing hearing aids in the audience would be picked up/recorded (this says something about demographics of audience... I suppose). In a live performance, this distraction goes (mostly) unnoticed. At home, it would probably drive me to turning off the hi-fi and letting those expensive WE 300B triodes cool off. Like a set of paint brushes, each mic lends itself to a style and technique. Being armed with only one brush (unless everything is about minute detail) isn't generally advised. Same analogy for microphones. I very much enjoy learning from others, but I also have a propensity to go out and make my own mistakes despite *sound* advise from others. (Repeating mistakes of others a second definition of insanity?) Best regards, Eric PS--This title's post, Mono Mia!, was taken from a Sound Practices magazine (out of print) article. Some people prefer vintage horns and Western Electric gear to VSTs and powered studio monitors. Nobody's right--it's what makes you sing that counts. -- next part -- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20130629/f4681280/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Giving Precedence to Ambisonics
On 29 Jun 2013, at 07:40, Dave Malham wrote: > On 28 June 2013 23:07, Goran Finnberg wrote: >> It´s all a blob of washed out sound in the middle with very little >> directional effects at all. A very spacious effect that is totally missing >> when I hear the same forces recorded via coincident mic techniques >> > All I can say is you've been listening to some very poor acoustics, then. I hear Goran's blob as well, even in great acoustics, although we might not agree about what's good acoustics :) It's very interesting that, as a classical recording engineer, I almost always end up with spaced mic setups. Perhaps it has to do with education, personal preference for certain aspects of sound quality (very multi-dimensional) or we might hear things differently. Some scientists are working on an article about this subject. It looks interesting: http://www.frontiersin.org/Auditory_Cognitive_Neuroscience/researchtopics/How_and_why_does_spatial-heari/1296 Here's a great comparison of different stereo mic setups. Around 03:40 the mics move from spaced to coincident. I personally can't imagine how anyone can find that an improvement but YMMV. http://www.youtube.com/watch?v=fguw5I6MxEo > Still, this is all a continuation of a "discussion" I have been having with > the beard Scotsman, Mike Williams, at AES conventions, over emails and in > person for the last three decades without every coming to a real agreement > - and we are still mates, much to my wife's surprise. There are plenty of things my wife and I don't agree about and we're still happily together. I think the same holds for recording techniques, as long as the violins come from the left. Kees de Visser Galaxy Classics ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Giving Precedence to Ambisonics
On 06/29/2013 07:40 AM, Dave Malham wrote: Still, this is all a continuation of a "discussion" I have been having with the beard Scotsman, Mike Williams, at AES conventions, over emails and in person for the last three decades without every coming to a real agreement - and we are still mates, much to my wife's surprise. :) the pleasure of discussing miking techniques with mr. williams :) i met mike at the last tonmeistertagung in köln, where my very unfortunate job was to tell him that we couldn't re-rig the speakers in precisely the 3d arrangement he wanted, just for his talk, so i went ahead and matrixed it onto an auro-3d setup. needless to say, he wasn't quite buying this idea (it was more a "show or no show" kind of decision), and i got a healthy dose of his microphone philosophy. while i wasn't convinced by everything he put forward, it was quite interesting nonetheless. the funniest aspect of that situation was that i found myself defending auro-3d (because that's what we had designed into that room) :-D i briefly mentioned that, if i had had my way, there would have been a HOA hemisphere in that room, and boy did i long for my asbestos underwear... -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
