Re: [Sursound] Catching the same fly twice (and a curious question)
If lacking a anechoic chamber, substitute it with: 1 - A large field covered with about half a meter of newfallen snow. 2 - On the top ridge of a gabled barn standing in a field. 3 - In the top of a large free standing tree. Some effort and dedication is needed to replace the cash expenditure to build a anechoic room :-) - Bo-Erik -Original Message- From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu] On Behalf Of etienne deleflie Sent: den 31 maj 2012 02:28 To: Surround Sound discussion group Subject: Re: [Sursound] Catching the same fly twice (and a curious question) -- Removed text Very similar concept to Alvin Lucier's composition I am sitting in a room ... except Lucier is amplifying the effect of the room .. and it is significant... and this suggests that the experiment should be done in an anechoic chamber ... because you will be capturing not just the effect of the microphone, and the limitations in the decoding, as well as the character of the speakers, but also the character of the room. Etienne ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Chasing flies with ambisoinics?
Hi Fons On 30/05/2012 18:24, Fons Adriaensen wrote: On Wed, May 30, 2012 at 02:10:22PM +0100, Augustine Leudar wrote: but anyone listening carefully would have heard a fly about 1 foot high ! This magnification effect has been reported many times. I wonder how much it has to do with playing back at too high levels. We do associate LF energy and size. Too much of it and the source 'must be' big. That's certainly important - kind of the other end of the scale of quite but distorted sounds can be interpreted as very loud sounds but with a distant source. For sound sources with perceivable angular extensions which are perceived as single objects (pianos, geese and steam loco's have been mentioned in the past), there is an even stronger cue in that for the angles to be right the perceived size of the object is set by the perceived distance which can in turn be modified if the reproduction space reverberation is dominant over the recorded reverberation. Whilst familiarity with the source can overlay some of this , even in York, where we are so familiar with geese ** that there's an informal ban on students recording them, we still find it difficult to hear anything other than Peter Lennox's giant geese when an Ambisonic recording is played back in a reverberant room. Dave ** At present I can see half a dozen Canada geese with young outside my window and some Greylags out on the lake - and I can hear a lot more! . PS - I gather you guys in Parma might be getting pretty shaken up by the earthquakes in Northern Italy - hope all is well there. -- These are my own views and may or may not be shared by my employer /*/ /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ /* Music Research Centre */ /* Department of Musichttp://music.york.ac.uk/; */ /* The University of York Phone 01904 322448*/ /* Heslington Fax 01904 322450*/ /* York YO10 5DD */ /* UK 'Ambisonics - Component Imaging for Audio' */ /*http://www.york.ac.uk/inst/mustech/3d_audio/; */ /*/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Catching the same fly twice (and a curious question)
On 31/05/2012 01:27, etienne deleflie wrote: .. perception. I wonder if perhaps direction is *not* that important to spatial audio. Ofcourse, it is a part, but is it central? This view leads to the questioning of the value of higher order ambisonics. I don't think people are actually allowed to do that on this list - you are definitely living dangerously! I sense the wagons circling already. Richard Dbson ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Catching the same fly twice (and a curious question)
On 30/05/2012 21:49, Eric Carmichel wrote: So how good is Ambisonics in reproducing the original auditory 'scene'? If the reconstructed wavefield is close to the original, then what happens when you record the Ambisonics system itself? Will the playback of this recording yield the same spatial information as the first recording did through an appropriate first- or n-order system? Or will the recording of the playback capture the so-called 'trickery,' thus making the recording-of-a-recording useless. Anybody tried this? I think I’ll give it a go using a four speaker arrangement (horizontal only) while playing a live recording of persons talking at eight equally-spaced locations around a Soundfield mic. Upon playback, I’ll place the Soundfield mic in the four-speaker arrangement, record this, and then listen to the recording of the recording. How much localization info do you believe will be lost? Could be fun, plus I’m a firm believer in learning by doing. Hi Eric, I have actually done this in the dim and distant past and I wasn't terribly happy with the result, iirc. Thinking about it now, I realise that the main problem was probably caused by the fact that it was a 'psychoacoustic compensated' decoder, with the shelf filters to move the decode from velocity to energy decode at a few hundred hertz, where the mkI Human Head approaches half a wavelength in size. It was also horizontal only. So, the system would only reproduce correctly over two dimensions and below a few hundred hertz. Above that it is not reproduced with exactitude - I think it was Jerome who showed this was equivalent to changing the speed of sound - someone correct me if I'm wrong - which I think would mean the correction in the Soundfield for capsule non-coincidence would be wrong. However, if a simple velocity only 3-d decode is used together with a sufficient number speakers, the reconstruction at the exact centre should be 'correct' with reducing degree of correctness as you move away from the exact centre in a way that is frequency dependent. So, at the exact centre, it should be picked up by the Soundfield as if it was the original sound field - at least up to the point where the physical extent of the Soundfield mic array means the capsule sampling points are outside the region of good reproduction. Dave -- These are my own views and may or may not be shared by my employer /*/ /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ /* Music Research Centre */ /* Department of Musichttp://music.york.ac.uk/; */ /* The University of York Phone 01904 322448*/ /* Heslington Fax 01904 322450*/ /* York YO10 5DD */ /* UK 'Ambisonics - Component Imaging for Audio' */ /*http://www.york.ac.uk/inst/mustech/3d_audio/; */ /*/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Chasing flies with ambisoinics?
Interestingly, he dinosaur size geese (John Leonard's recording when geese go bad) was played in a field, speaker radius 15-20 metres. And the passing motorbike was impressively large, too. AS a rule of thumb, I've always found that one needs to bear in mind the speaker array radius when deciding on the source-mic relationships. Even in a not-very-reverberant outdoor setting, there seems to be some perceptual constancy for speaker distance - this could be using visual, prior knowledge, auditory-only or combination cues. We've observed the same thing for movement plausibility, with recordings of rolling balls. They have to change angle only as much as the rolling sound (which gives reasonable speed cues) would allow, for a particular speaker distance (range). So, if you want to 'scale up' to a bigger rig, then you need to re-pan (where discrete mic recordings are used) - the perceptual understanding of speed draws on far more than change-of-subtended-angle - and when the cues clearly conflict, the mediated nature 'leaps out' at you. Dr Peter Lennox School of Technology University of Derby, UK tel: 01332 593155 e: p.len...@derby.ac.uk -Original Message- From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu] On Behalf Of Dave Malham Sent: 31 May 2012 09:26 To: Surround Sound discussion group Subject: Re: [Sursound] Chasing flies with ambisoinics? Hi Fons On 30/05/2012 18:24, Fons Adriaensen wrote: On Wed, May 30, 2012 at 02:10:22PM +0100, Augustine Leudar wrote: but anyone listening carefully would have heard a fly about 1 foot high ! This magnification effect has been reported many times. I wonder how much it has to do with playing back at too high levels. We do associate LF energy and size. Too much of it and the source 'must be' big. That's certainly important - kind of the other end of the scale of quite but distorted sounds can be interpreted as very loud sounds but with a distant source. For sound sources with perceivable angular extensions which are perceived as single objects (pianos, geese and steam loco's have been mentioned in the past), there is an even stronger cue in that for the angles to be right the perceived size of the object is set by the perceived distance which can in turn be modified if the reproduction space reverberation is dominant over the recorded reverberation. Whilst familiarity with the source can overlay some of this , even in York, where we are so familiar with geese ** that there's an informal ban on students recording them, we still find it difficult to hear anything other than Peter Lennox's giant geese when an Ambisonic recording is played back in a reverberant room. Dave ** At present I can see half a dozen Canada geese with young outside my window and some Greylags out on the lake - and I can hear a lot more! . PS - I gather you guys in Parma might be getting pretty shaken up by the earthquakes in Northern Italy - hope all is well there. -- These are my own views and may or may not be shared by my employer /*/ /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ /* Music Research Centre */ /* Department of Musichttp://music.york.ac.uk/; */ /* The University of York Phone 01904 322448*/ /* Heslington Fax 01904 322450*/ /* York YO10 5DD */ /* UK 'Ambisonics - Component Imaging for Audio' */ /*http://www.york.ac.uk/inst/mustech/3d_audio/; */ /*/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound _ The University of Derby has a published policy regarding email and reserves the right to monitor email traffic. If you believe this email was sent to you in error, please notify the sender and delete this email. Please direct any concerns to info...@derby.ac.uk. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Catching the same fly twice (and a curious question)
Dave said: Here, to any extent, I depart from Gibson. With sufficiently advanced technology there comes a point at which the effort required to suspend disbelief is so small as to be negligible. I was reading a report on a paper a few months ago (I think in New Scientist) where the authors were suggesting that some on-line gamers have difficult perceiving the real world as actually being real when they come out of the games. This suggests that even with the relatively poor systems we have at present (compared with what we know will be possible in future since it only needs evolution, not revolution, in the technology), the barrier to suspension has already become low. Now I am not suggesting that we would be able to recreate exactly a particular person's experience of going to a particular concert - at least, without Total Recall type technology (and, despite the advances with fMRI technology we are a lng way off that) - but I do think we will be able to have a pretty good shot at giving someone the experience of going to that concert themselves This is The Matrix, anything written by Philip K Dick, and before that, Plato in his Cave metaphor. It is essentially unprovable: ...If physically perfected artificial three-dimensional auditory environments were feasible, would the artificial product be as entirely realistic to perception as the real thing? If not, what ingredient is missing? If so, what would philosophically distinguish real and artificial? Is such a distinction necessary? ...Plato's metaphor for humans' grasp of reality as nothing more than shadows on a cave wall, being constrained by the limitations of what is available to sensation, is relevant today; especially for artificial environments. It is an early example of one strand of thinking about perception as mediated by sensation, inevitably a poor copy of reality. Whilst philosophers are entirely comfortable with such thought experiments, there is no obvious pragmatic way to investigate such speculations. By definition, if an artificial environment is detectable as such, then it is imperfectly executed and the hypothetical position has not been matched. On the other hand, if the artificial environment were perfectly rendered, there would be no way to prove its artificiality. [ my thesis, some years ago] So, maybe the whole point of making artificial environments is not that we can perfect them, but that, in doing so, we come to understand more about the perceptually relevant constituents of real environments. So it's the journey, not the destination..? Peter Lennox _ The University of Derby has a published policy regarding email and reserves the right to monitor email traffic. If you believe this email was sent to you in error, please notify the sender and delete this email. Please direct any concerns to info...@derby.ac.uk. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Catching the same fly twice (and a curious question)
On 31 May 2012 12:52, Peter Lennox p.len...@derby.ac.uk wrote: Actually, there is something here, though I do wonder if it is pathological. I've met people who told me that such-and-such a driving game was fantastically realistic. I found it stilted, leaden and profoundly unrealistic. I've even met people who, having 'virtually' driven a particular race track, upon actually driving it, were actually surprised that their lap performance in the real was inferior. But on the other hand, was it better or worse than if they hadn't played the game? Research has been reported showing that performance of subjects in accomplishing tasks - especially those requiring hand/eye coordination - is (significantly) better if they first work in simulations than if they hadn't done so. This is, of course, very worrying (or should be) for those who claim playing violent video games has no effect in the real world. Of course, we do make good use of training simulators for pilots, and I presume (hope) they are very much more 'realistic'. However, what they are simulating is the cockpit of an aircraft which in itself constitutes a partially mediated environment Ah - but so's a racing car... Dave -- These are my own views and may or may not be shared by my employer Dave Malham Music Research Centre Department of Music The University of York Heslington York YO10 5DD UK Phone 01904 322448 Fax 01904 322450 'Ambisonics - Component Imaging for Audio' ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Chasing flies with ambisoinics?
Hi Dave, This magnification effect has been reported many times. I wonder how much it has to do with playing back at too high levels. We do associate LF energy and size. Too much of it and the source 'must be' big. That's certainly important - kind of the other end of the scale of quite but distorted sounds can be interpreted as very loud sounds but with a distant source. For sound sources with perceivable angular extensions which are perceived as single objects (pianos, geese and steam loco's have been mentioned in the past), there is an even stronger cue in that for the angles to be right the perceived size of the object is set by the perceived distance which can in turn be modified if the reproduction space reverberation is dominant over the recorded reverberation. That is certainly the case for the new 3rd order AMB (horizontal only) system installed recently in la Casa del Suono (which is a small church, so quite reverberant). It works great for concerts, which is what is was designed to do, but for most recorded material indeed any sense of distance is lost. I did a small experiment a few weeks ago, and was quite surprised by the result. In a concert we did at the CdS there were three pieces for solo flute and 'tape'. We got the 'tapes' as CDs of course. The artistic director of the festival asked me if I could somehow 'spatialize' the tapes instead of just playing them via two speakers. There wasn't much time to do anything fancy, so I created six filters, one for each of X,Y,U,V,P,Q which would distribute a mono source in function of frequency, with one full cycle in azimuth for each octave. In fact I made two sets, one going clockwise and the second in the opposite sense. The tapes were all electronic noises, nothing you could recognise as a natural sound, and it worked quite well. Afterwards I took the filter set to the studio at the CdM which also has 3rd order monitoring, and used it on some non-electronic music recordings. Of course this produces quite unnatural effects, sounds which you know as from a single source are split in direction (but 2nd and 4th harmonic would coincide with the fundamental). Each of the speaker signals separately is extremely coloured, and when you solo them in the right order you get the 'infinitely ascending pitch' effect. What surprised me is that nobody could associate pitch and speakers. I somehow expected it would be obvious that e.g. all 'C' notes would come from the same direction, and that one would be able to identify the pitch of each speaker when listening to the complete signal. But that was not the case, and you had to go quite close to any speaker in order to notice there was something strange with the sound it produced. PS - I gather you guys in Parma might be getting pretty shaken up by the earthquakes in Northern Italy - hope all is well there. Here in Parma there's no major damage so far, but in the region just NE of Modena (60..70 km from here) it's dire misery. 16 people died on monday, mostly employees who were just resuming work a week after the first shock. And very probably it's not finished, there are lots of small tremors all day and night, and some more big ones can be expected. Ciao, -- 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
Re: [Sursound] Chasing flies with ambisoinics?
Hi Fons On 31/05/2012 14:42, Fons Adriaensen wrote: I did a small experiment a few weeks ago, and was quite surprised by the result. In a concert we did at the CdS there were three pieces for solo flute and 'tape'. We got the 'tapes' as CDs of course. The artistic director of the festival asked me if I could somehow 'spatialize' the tapes instead of just playing them via two speakers. There wasn't much time to do anything fancy, so I created six filters, one for each of X,Y,U,V,P,Q which would distribute a mono source in function of frequency, with one full cycle in azimuth for each octave. In fact I made two sets, one going clockwise and the second in the opposite sense. The tapes were all electronic noises, nothing you could recognise as a natural sound, and it worked quite well. Afterwards I took the filter set to the studio at the CdM which also has 3rd order monitoring, and used it on some non-electronic music recordings. Of course this produces quite unnatural effects, sounds which you know as from a single source are split in direction (but 2nd and 4th harmonic would coincide with the fundamental). Each of the speaker signals separately is extremely coloured, and when you solo them in the right order you get the 'infinitely ascending pitch' effect. What surprised me is that nobody could associate pitch and speakers. I somehow expected it would be obvious that e.g. all 'C' notes would come from the same direction, and that one would be able to identify the pitch of each speaker when listening to the complete signal. But that was not the case, and you had to go quite close to any speaker in order to notice there was something strange with the sound it produced. That's interesting - it kind of chimes with some experiments I have been doing recently with digital recreations of Gerzon's spreaders, which used phase shift based processing. Although technically they are doing what is described in MAG's original hand written reports, the way they sound doesn't really correspond very closely to description of how they should sound in the same report. Whilst a broadband sound processed through one of my pluggins (imaginatively named 'mgspreadpan') does lose the sense of being a point source as you turn the spread up, there's no clear feeling that sounds of particular frequencies are coming from a particular direction. Have you compared the results of having separate X,Y,U,V,P,Q filters to generate the panning (which is how I interpret what you say above) with pre-filtering the sounds then panning the filter outputs? PS - I gather you guys in Parma might be getting pretty shaken up by the earthquakes in Northern Italy - hope all is well there. Here in Parma there's no major damage so far, but in the region just NE of Modena (60..70 km from here) it's dire misery. 16 people died on monday, mostly employees who were just resuming work a week after the first shock. And very probably it's not finished, there are lots of small tremors all day and night, and some more big ones can be expected. Glad to hear that you are ok and hope that it stays that way, All the best Dave -- These are my own views and may or may not be shared by my employer /*/ /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ /* Music Research Centre */ /* Department of Musichttp://music.york.ac.uk/; */ /* The University of York Phone 01904 322448*/ /* Heslington Fax 01904 322450*/ /* York YO10 5DD */ /* UK 'Ambisonics - Component Imaging for Audio' */ /*http://www.york.ac.uk/inst/mustech/3d_audio/; */ /*/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Chasing flies with ambisoinics?
Thats pretty similar to an example I heard the other day. A composer had split the sound of a cello into different frequency bands and dispersed them around a lot of loudspeakers (in a line if I remember correctly) each one playing a different frequency - imagine his dissapointment when the human auditroy system summed all the frequencies back up again and and allocated the sound source and its entire set of frequency bands to one blurry spot. The solution it turned out to be that he had to decorrolate and desynchronise (slightly) the signals and frequancy bands to each speaker and then , and only then, did he achieve the spatialisation effect he looked for. Gary Kendal explains it very well in his paper why things don't work section 3.8. Why do I still hear single image when I put the harmonics of a sound in different loudspeakers? What surprised me is that nobody could associate pitch and speakers. I somehow expected it would be obvious that e.g. all 'C' notes would come from the same direction, and that one would be able to identify the pitch of each speaker when listening to the complete signal. But that was not the case, and you had to go quite close to any speaker in order to notice there was something strange with the sound it produced. -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20120531/82abef66/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
[Sursound] Doppler ILLUSION (vs. shift) and more
), then iterations of the recording made through the system should yield recordings with identical, physically measurable attributes. By the way, thanks Dave for sharing insight and experience regarding your recording of a recording. I have access to a fairly large, semi-anechoic room (all walls, floor and ceiling well treated) that could be useful for such an experiment. I'll keep you posted. As always, I greatly appreciate everyone’s help and insight! Best always, Eric -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20120531/1d947194/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
