Dear all, I was wondering how, knowing the diameter of a speaker octagon, using 1st or 3rd Order ambisonics, to calculate precisely the dimensions of the sweet spot area. Any ideas? Many thanks
tom On 6 Nov 2012, at 17:00, sursound-requ...@music.vt.edu wrote: > Send Sursound mailing list submissions to > sursound@music.vt.edu > > To subscribe or unsubscribe via the World Wide Web, visit > https://mail.music.vt.edu/mailman/listinfo/sursound > or, via email, send a message with subject or body 'help' to > sursound-requ...@music.vt.edu > > You can reach the person managing the list at > sursound-ow...@music.vt.edu > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Sursound digest..." > > > When replying, please remember to edit your Subject line to that of the > original message you are replying to, so it is more specific than "Re: > Contents of Sirsound-list digest..." so that it matches the post you are > replying to. > > Also, please EDIT the quoted post so that it is not the entire digest, but > just the post you are replying to. > > > Today's Topics: > > 1. Which order (but not extactly high order)? (Eric Carmichel) > 2. Re: Vestibular response, HRTF database, and now with added > height... (Peter Lennox) > 3. Re: Vestibular response, HRTF database, and now with added > height... (Dave Malham) > 4. Re: Vestibular response, HRTF database, and now with added > height... (Peter Lennox) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 5 Nov 2012 15:59:19 -0800 (PST) > From: Eric Carmichel <e...@elcaudio.com> > Subject: [Sursound] Which order (but not extactly high order)? > To: "sursound@music.vt.edu" <sursound@music.vt.edu> > Message-ID: > <1352159959.33851.yahoomail...@web2802.biz.mail.ne1.yahoo.com> > Content-Type: text/plain; charset="us-ascii" > > Greetings, > I would like to model microphone pickup patterns in conjunction with HRTFs > and Ambisonic recordings that I've made. To give a specific example, I would > like model a miniature supercardiod mic, pointed forward, that is located > proximal (or superior) to the pinna. This would be akin to a directional mic > on a hearing aid or CI processor. The HRTF can be approximate, as the mic is > likely to be placed slightly above the pinna and close to the head, not right > at the opening of the ear canal. Some mics, however, are located in the > concha, so the IRs from the Listen Project would approximate the mic > placement, but not the mic's polar pattern. > I have recordings of cafeterias and public spaces that I made using a > TetraMic. VVMic allows me to create first-order mic patterns that can be > rotated in space. This alone is useful, but does not include the acoustic > shadow that would be created by a hearing aid wearer's head. I have the > Harpex VST, too. Harpex includes the HRIRs from the Listen Project (Svein, > please correct me if I'm wrong on this), thus making binaural simulations a > snap. But to get an HRTF that includes a specific mic pick-up pattern is a > little trickier. > I had initially used VVMic to create the mic pattern I wanted, and then aimed > it to the direction I wanted. Input was B-formatted wav files. The resulting > output is a single channel, or N identical channels if I want to create N > tracks. I created 4 tracks and used these as pseudo B-formatted material in > Harpex. > The other "order" would be to create a stereo (binaural) output via Harpex > from the original (authentic) B-formatted material. Then one of the two > channels, L or R, could be made into four identical tracks that can be fed to > VVMic to get the intended polar response. The four tracks, of course, are not > B-format. > A bit of head scratching tells me neither method outlined above is correct. > At least the binaural output from Harpex should be equivalent to an > omnidirectional mic placed at an ear's concha (ITE hearing aids), and that > could be used for simulations of electric listening. But I'd really like to > model hybrid devices that combine both electric (cochlear implant) and > acoustic (hearing aid) stimulation. It seems that using Ambisonic recordings > without the need for loudspeakers would be an elegant way to simulate CI > listening in 3-D environments, but using normal-hearing listeners. > > Regarding my recent post (vestibular-auditory interactions and HRTFs): Thanks > to Peter L. for making my clumsy wording clearer and to Dave M. for making > the idea more direct and to the point. I have to be careful when referencing > the anatomical horizontal plane versus the horizontal plane that lies > perpendicular to gravity. Although a bit off topic of Ambisonics, the post > did directly relate to spatial hearing. Because it's easy to do virtual mic > rotations with Ambisonic material, Ambisonics could be a useful tool for > studying vestibular-auditory interactions. > Thanks to everyone, > Eric > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121105/7ac6a6d2/attachment.html> > > > ------------------------------ > > Message: 2 > Date: Tue, 6 Nov 2012 11:09:18 +0000 > From: Peter Lennox <p.len...@derby.ac.uk> > Subject: Re: [Sursound] Vestibular response, HRTF database, and now > with added height... > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: > > <28f33490c302424e98cc6dc2531b2048cd3d82e...@mkt-mbx01.university.ds.derby.ac.uk> > > Content-Type: text/plain; charset="us-ascii" > > well, I think it's a big jump, so to speak to try to get funding for that. > > I have a much more modest proposal: > > Is auditory spatial perception and performance similar in all regions? - I > have a strong suspicion that it's different in the Maldives. Further, I think > it may be that, if you take someone that has been tested in, say, England, > then transport them to the Maldives and test, looking for changes in > performance over a 2 month period, one might find a progressive change. Then > bring them back for a two month, repeating the test procedure. Then back to > the Maldives, testing if the change in performance is similar, or indeed more > rapid, the second time around. > If significant results are obtained, we next try Bali. and so on. > This will be much cheaper than the zero-G proposal > > In the interests of science, I am prepared to volunteer as a guinea pig, even > if it means turning my back on my chances of being promoted to fourth > assistant to the deputy office manager - that's how dedicated to science I am! > Dr Peter Lennox > > School of Technology, > Faculty of Arts, Design and Technology > University of Derby, UK > e: p.len...@derby.ac.uk > t: 01332 593155 > ________________________________________ > From: sursound-boun...@music.vt.edu [sursound-boun...@music.vt.edu] On Behalf > Of Dave Malham [dave.mal...@york.ac.uk] > Sent: 05 November 2012 16:28 > To: Surround Sound discussion group > Subject: Re: [Sursound] Vestibular response, HRTF database, and now with > added height... > > Hi Peter, > Like I just said - needs experiments in zero G. I wonder what the > acoustics in the ISS are like? Might be easier to organise decent > acoustics in a Vomit Comet > (http://en.wikipedia.org/wiki/Reduced_gravity_aircraft) especially as > the padding already there would help. Now, where do we apply for > funding?? > > Dave > > On 5 November 2012 14:18, Peter Lennox <p.len...@derby.ac.uk> wrote: >> Eric, some interesting thoughts there, thanks. >> One or two thoughts in reaction: >> 1) you say " There have been a lot of studies regarding localization in the >> transverse (horizontal) plane" - I know its quite common to conflate these, >> but (as implied in your later thought experiment) - it's worth pointing out >> that "horizontal" is specified as perpendicular to gravity. When a person is >> standing or sitting straight, then if the head is not tilted then the >> conflation is permissible. But. People tilt and move their heads all the >> time, so acuity in hearing in the transverse plane is not the same as acuity >> in the horizontal plane >> >> 2) Your question about acuity when the body is not in that 'usual' >> orientation: I've thought the same thing, though the other way around - I >> put people flat on their backs, then played ambisonic material tilted >> through 90 degrees, to see if they got some different experience. So, I was >> interested in perception in the vertical, but using that transverse plane. >> The experience was different, but inconclusive in that it wasn't a >> controlled experiment, of course. I found that identification of source >> direction was less good than I'd anticipated. BUT - actually, (going back to >> experiences whilst camping - I've lain awake in the countryside thinking >> about these things) - listening (especially for direction) with your head so >> close to the ground is certainly an unfamiliar experience. You've messed up >> a lot of the pinnae effects. Interaural differences may well be affected. >> You've got a peculiar pattern of very early reflections (from the ground >> next to your ears). Most importantly , > y >> ou're listening to sources in the sky, with no reflective and occlusive >> bodies around them. There's no 'ground effect' of the sort that a standing >> or sitting person will get - that it, early reflected material that has >> interacted with the ground, including filtering by surface features, clutter >> (material objects and detritus have a tendency to be near the ground due to >> gravity...) so, overall, hearing in that area just won't be the same. >> The above might partly account for why, in your experiment, hearing in the >> horizontal might seem better than it ought - there are simply more cues >> available for sources at or near the ground? However, in the camping >> example, I did find increased instances of reversals. >> >> So I had thought there might be an interaction between gravity and spatial >> hearing, but realised that some of it is just down to physics - the sky >> really is different from the ground, we really are sort of "2.5 d" hearers >> (and thinkers?). I'd also wondered whether distance(range) perception might >> differ with direction. It does (items seem nearer), but more to do with the >> physics of the matter - for sources in the sky, sometimes (not always!) >> there is only a direct signal path. So, distance perception as the product >> of the direct/indirect ratio doesn't seem quite the right formulation. >> >> These things need some decent experimentation, it seems to me >> >> Cheers >> ppl >> >> >> Dr. Peter Lennox >> >> School of Technology, >> Faculty of Arts, Design and Technology >> University of Derby, UK >> e: p.len...@derby.ac.uk >> t: 01332 593155 >> >> -----Original Message----- >> From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu] >> On Behalf Of Eric Carmichel >> Sent: 03 November 2012 18:54 >> To: sursound@music.vt.edu >> Subject: [Sursound] Vestibular response, HRTF database, and more >> >> Greetings, >> Mostly through serendipity, I have had the pleasure and privilege of great >> teachers. I studied recording arts under Andy Seagle (andyseagle.com) who >> recorded Paul McCartney, Hall & Oats, and numerous others. My doc committee >> included Bill Yost, who is widely known among the spatial hearing folks. >> And, of course, I've learned a lot about Ambisonics from people on this list >> as well as a plethora of technical articles. >> >> I recently sent an email to Bill with the following question/scenario. I >> thought others might wish to give this thought, too, as it gets into HRTFs. >> >> There have been a lot of studies regarding localization in the transverse >> (horizontal) plane. We also know from experiments how well (or poorly) we >> can localize sound in the frontal and sagittal planes. By simply tilting >> someone back 90 degrees, his/her ears shift to another plane. This is >> different from shifting the loudspeaker arrangement to another plane because >> the semicircular canals are now in a different orientation. If a circular >> speaker array was setup in the coronal plane and the person was lying down, >> then his/her ears would be oriented in such a way that the speakers now >> circle the head in the same fashion as they would in the horizontal plane >> when the person is seated or standing. It's a "static" vestibular change, >> and gravity acting on the semicircular canals (and body) lets us know which >> way is up. But do we have the same ability to localize when the body is >> positioned in different orientations, even when the sources "follow" the >> orientation (as is the case > in >> the above example)? How about localization in low-g environments (e.g. >> space docking)? The question came to me while camping. I seem able to >> pinpoint sounds quite well in the (normal) horizontal plane despite a skewed >> HRTF while lying down (and somewhat above ground). >> >> On another (but related) topic, I have downloaded the HRTF data from the >> Listen Project, and have been sorting the participant's morphological >> features. I have this in an Excel spreadsheet, and am converting this to an >> Access database. Using the data, one can pick an "appropriate" HRTF starting >> with gross anatomical features (such as headsize) and whittle it down to >> minute features (such as concha depth or angle). I find HRTF discussions >> interesting, but still argue that headphones and whole-body transfer >> functions make a difference, too. Insert phones destroy canal resonance, >> whereas an earcup with active drivers may have a large "equivalent" volume, >> thus minimizing external meatus/earcup interaction (a mix and match of >> resonances). Because of this, there can be no ideal HRTF, even when it >> matches the listener. >> >> While listening to HRTF demos, the notion of auditory streaming and auditory >> scenes came to mind. Some sounds were externalized, but other sounds of >> varying frequencies, while emanating from the same sound source, appeared in >> my head. The end result was that the externalized sounds provided a >> convincing (or at least fun) illusion, but problems do persist. A stringent >> evaluation of HRTF / binaural listening via headphones would require >> breaking the sounds into bands and seeing if a sound's constituent >> components remain outside of the head. When doing so, a brick-wall filter >> wouldn't be necessary, but a filter that maintains phase coherency would be >> recommended. The demo I refer to was that of a helicopter flying overhead. >> Though I haven't done this (yet), it would be interesting to use FFT >> filtering to isolate the turbine whine (a high-pitched sound) from the >> chopper's blades. The high-pitched sound appeared to be in my head, whereas >> the helicopter as a whole seemed extern a > li >> zed. Again, an individualized HRTF and different phones may yield different >> results. Side note: Be careful using FFT filtering--it can yield some >> peculiar artifacts. >> >> I am hoping to use headtracking in conjunction with VVMic to model different >> hearing aid and cochlear implant mics in space. This offers the advantage of >> presenting real-world listening environments via live recordings to >> study/demonstrate differences in mic polar patterns (at least first-order >> patterns) and processing without the need for a surround loudspeaker system. >> In fact, it's ideal for CI simulations because an actual CI user never gets >> a pressure at the eardrum that then travels along the basilar membrane, >> ultimately converted to nerve impulses. With VVMic and HRTF data, I should >> be able to provide simulations of mics located on a listener's head and then >> direct the output to one or both ears. This does not represent spatial >> listening, but it does represent electric (CI) hearing in space. Putting a >> normal-hearing listener in a surround sound environment with mock processors >> and real mics doesn't work because you can't isolate the outside (surround) >> sound from the i > nt >> ended simulation, even with EAR foam plugs and audiometric insert phones. >> VVMic and live recordings via Ambisonics is a solution to creating >> "electric" listening in the real world. Again, I'm referring solely to CI >> simulations. With the advent of electric-acoustic stimulation (EAS), more >> than one mic is used per ear: One for the CI and a second for the HA. >> Combinations of polar patterns can be created. Respective frequency >> responses and processing can be sent to one or two ears (diotic and dichotic >> situations). One caveat for using vocoding to mimic CIs is that the acoustic >> simulation (and therefore stimulation) still necessitates a traveling wave >> along the normal-hearing listener's basilar membrane. The time it takes to >> establish a wave peak is not instantaneous (though compressional waves in >> the the inner ear are virtually instantaneous), and I believe a time-domain >> component to inner ear (mechanical) action can't easily be excluded when >> using "acoustic" simulation of CIs. I suppose I could look at data from >> BAERs and the Greenwood approximati o > n >> to account for the time-frequency interaction. Just some thinking... and >> ideas to share with others interested in hearing impairments. >> >> >> By the way, Teemko, if you're reading this, just wanted to let you know that >> Bill Yost said he'd read your thesis over the weekend. I notice that Bill >> and Larry Revit are in your references list. Larry isn't a fan of >> Ambisonics--said to me in a phone communication that it sounds "tinny". I >> suppose it does if one were to listen through laptop speakers or from poor >> source material. Not sure what his source was. >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: >> <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121103/837528f1/attachment.html> >> _______________________________________________ >> 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 > > > > -- > As of 1st October 2012, I have retired from the University, so this > disclaimer is redundant.... > > > These are my own views and may or may not be shared by my employer > > Dave Malham > Ex-Music Research Centre > Department of Music > The University of York > Heslington > York YO10 5DD > UK > > 'Ambisonics - Component Imaging for 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. > > > ------------------------------ > > Message: 3 > Date: Tue, 6 Nov 2012 11:18:27 +0000 > From: Dave Malham <dave.mal...@york.ac.uk> > Subject: Re: [Sursound] Vestibular response, HRTF database, and now > with added height... > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: > <CAPw+1zRew_c7xhUCmDZC9-Qjfp_=7wknzo7yujsmlmjvxup...@mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > And, of course, it would be essential to test for the effects of age > on the rapidity of change, so I guess I will be forced to come out of > retirement in order to provide a suitable subject without > inconveniencing anyone else... > > Dave > > On 6 November 2012 11:09, Peter Lennox <p.len...@derby.ac.uk> wrote: >> well, I think it's a big jump, so to speak to try to get funding for that. >> >> I have a much more modest proposal: >> >> Is auditory spatial perception and performance similar in all regions? - I >> have a strong suspicion that it's different in the Maldives. Further, I >> think it may be that, if you take someone that has been tested in, say, >> England, then transport them to the Maldives and test, looking for changes >> in performance over a 2 month period, one might find a progressive change. >> Then bring them back for a two month, repeating the test procedure. Then >> back to the Maldives, testing if the change in performance is similar, or >> indeed more rapid, the second time around. >> If significant results are obtained, we next try Bali. and so on. >> This will be much cheaper than the zero-G proposal >> >> In the interests of science, I am prepared to volunteer as a guinea pig, >> even if it means turning my back on my chances of being promoted to fourth >> assistant to the deputy office manager - that's how dedicated to science I >> am! >> Dr Peter Lennox >> >> School of Technology, >> Faculty of Arts, Design and Technology >> University of Derby, UK >> e: p.len...@derby.ac.uk >> t: 01332 593155 >> ________________________________________ >> From: sursound-boun...@music.vt.edu [sursound-boun...@music.vt.edu] On >> Behalf Of Dave Malham [dave.mal...@york.ac.uk] >> Sent: 05 November 2012 16:28 >> To: Surround Sound discussion group >> Subject: Re: [Sursound] Vestibular response, HRTF database, and now with >> added height... >> >> Hi Peter, >> Like I just said - needs experiments in zero G. I wonder what the >> acoustics in the ISS are like? Might be easier to organise decent >> acoustics in a Vomit Comet >> (http://en.wikipedia.org/wiki/Reduced_gravity_aircraft) especially as >> the padding already there would help. Now, where do we apply for >> funding?? >> >> Dave >> >> On 5 November 2012 14:18, Peter Lennox <p.len...@derby.ac.uk> wrote: >>> Eric, some interesting thoughts there, thanks. >>> One or two thoughts in reaction: >>> 1) you say " There have been a lot of studies regarding localization in the >>> transverse (horizontal) plane" - I know its quite common to conflate these, >>> but (as implied in your later thought experiment) - it's worth pointing out >>> that "horizontal" is specified as perpendicular to gravity. When a person >>> is standing or sitting straight, then if the head is not tilted then the >>> conflation is permissible. But. People tilt and move their heads all the >>> time, so acuity in hearing in the transverse plane is not the same as >>> acuity in the horizontal plane >>> >>> 2) Your question about acuity when the body is not in that 'usual' >>> orientation: I've thought the same thing, though the other way around - I >>> put people flat on their backs, then played ambisonic material tilted >>> through 90 degrees, to see if they got some different experience. So, I was >>> interested in perception in the vertical, but using that transverse plane. >>> The experience was different, but inconclusive in that it wasn't a >>> controlled experiment, of course. I found that identification of source >>> direction was less good than I'd anticipated. BUT - actually, (going back >>> to experiences whilst camping - I've lain awake in the countryside thinking >>> about these things) - listening (especially for direction) with your head >>> so close to the ground is certainly an unfamiliar experience. You've messed >>> up a lot of the pinnae effects. Interaural differences may well be >>> affected. You've got a peculiar pattern of very early reflections (from the >>> ground next to your ears). Most importantl y > , >> y >>> ou're listening to sources in the sky, with no reflective and occlusive >>> bodies around them. There's no 'ground effect' of the sort that a standing >>> or sitting person will get - that it, early reflected material that has >>> interacted with the ground, including filtering by surface features, >>> clutter (material objects and detritus have a tendency to be near the >>> ground due to gravity...) so, overall, hearing in that area just won't be >>> the same. >>> The above might partly account for why, in your experiment, hearing in the >>> horizontal might seem better than it ought - there are simply more cues >>> available for sources at or near the ground? However, in the camping >>> example, I did find increased instances of reversals. >>> >>> So I had thought there might be an interaction between gravity and spatial >>> hearing, but realised that some of it is just down to physics - the sky >>> really is different from the ground, we really are sort of "2.5 d" hearers >>> (and thinkers?). I'd also wondered whether distance(range) perception might >>> differ with direction. It does (items seem nearer), but more to do with the >>> physics of the matter - for sources in the sky, sometimes (not always!) >>> there is only a direct signal path. So, distance perception as the product >>> of the direct/indirect ratio doesn't seem quite the right formulation. >>> >>> These things need some decent experimentation, it seems to me >>> >>> Cheers >>> ppl >>> >>> >>> Dr. Peter Lennox >>> >>> School of Technology, >>> Faculty of Arts, Design and Technology >>> University of Derby, UK >>> e: p.len...@derby.ac.uk >>> t: 01332 593155 >>> >>> -----Original Message----- >>> From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu] >>> On Behalf Of Eric Carmichel >>> Sent: 03 November 2012 18:54 >>> To: sursound@music.vt.edu >>> Subject: [Sursound] Vestibular response, HRTF database, and more >>> >>> Greetings, >>> Mostly through serendipity, I have had the pleasure and privilege of great >>> teachers. I studied recording arts under Andy Seagle (andyseagle.com) who >>> recorded Paul McCartney, Hall & Oats, and numerous others. My doc committee >>> included Bill Yost, who is widely known among the spatial hearing folks. >>> And, of course, I've learned a lot about Ambisonics from people on this >>> list as well as a plethora of technical articles. >>> >>> I recently sent an email to Bill with the following question/scenario. I >>> thought others might wish to give this thought, too, as it gets into HRTFs. >>> >>> There have been a lot of studies regarding localization in the transverse >>> (horizontal) plane. We also know from experiments how well (or poorly) we >>> can localize sound in the frontal and sagittal planes. By simply tilting >>> someone back 90 degrees, his/her ears shift to another plane. This is >>> different from shifting the loudspeaker arrangement to another plane >>> because the semicircular canals are now in a different orientation. If a >>> circular speaker array was setup in the coronal plane and the person was >>> lying down, then his/her ears would be oriented in such a way that the >>> speakers now circle the head in the same fashion as they would in the >>> horizontal plane when the person is seated or standing. It's a "static" >>> vestibular change, and gravity acting on the semicircular canals (and body) >>> lets us know which way is up. But do we have the same ability to localize >>> when the body is positioned in different orientations, even when the >>> sources "follow" the orientation (as is the cas e >> in >>> the above example)? How about localization in low-g environments (e.g. >>> space docking)? The question came to me while camping. I seem able to >>> pinpoint sounds quite well in the (normal) horizontal plane despite a >>> skewed HRTF while lying down (and somewhat above ground). >>> >>> On another (but related) topic, I have downloaded the HRTF data from the >>> Listen Project, and have been sorting the participant's morphological >>> features. I have this in an Excel spreadsheet, and am converting this to an >>> Access database. Using the data, one can pick an "appropriate" HRTF >>> starting with gross anatomical features (such as headsize) and whittle it >>> down to minute features (such as concha depth or angle). I find HRTF >>> discussions interesting, but still argue that headphones and whole-body >>> transfer functions make a difference, too. Insert phones destroy canal >>> resonance, whereas an earcup with active drivers may have a large >>> "equivalent" volume, thus minimizing external meatus/earcup interaction (a >>> mix and match of resonances). Because of this, there can be no ideal HRTF, >>> even when it matches the listener. >>> >>> While listening to HRTF demos, the notion of auditory streaming and >>> auditory scenes came to mind. Some sounds were externalized, but other >>> sounds of varying frequencies, while emanating from the same sound source, >>> appeared in my head. The end result was that the externalized sounds >>> provided a convincing (or at least fun) illusion, but problems do persist. >>> A stringent evaluation of HRTF / binaural listening via headphones would >>> require breaking the sounds into bands and seeing if a sound's constituent >>> components remain outside of the head. When doing so, a brick-wall filter >>> wouldn't be necessary, but a filter that maintains phase coherency would be >>> recommended. The demo I refer to was that of a helicopter flying overhead. >>> Though I haven't done this (yet), it would be interesting to use FFT >>> filtering to isolate the turbine whine (a high-pitched sound) from the >>> chopper's blades. The high-pitched sound appeared to be in my head, whereas >>> the helicopter as a whole seemed exter n > a >> li >>> zed. Again, an individualized HRTF and different phones may yield different >>> results. Side note: Be careful using FFT filtering--it can yield some >>> peculiar artifacts. >>> >>> I am hoping to use headtracking in conjunction with VVMic to model >>> different hearing aid and cochlear implant mics in space. This offers the >>> advantage of presenting real-world listening environments via live >>> recordings to study/demonstrate differences in mic polar patterns (at least >>> first-order patterns) and processing without the need for a surround >>> loudspeaker system. In fact, it's ideal for CI simulations because an >>> actual CI user never gets a pressure at the eardrum that then travels along >>> the basilar membrane, ultimately converted to nerve impulses. With VVMic >>> and HRTF data, I should be able to provide simulations of mics located on a >>> listener's head and then direct the output to one or both ears. This does >>> not represent spatial listening, but it does represent electric (CI) >>> hearing in space. Putting a normal-hearing listener in a surround sound >>> environment with mock processors and real mics doesn't work because you >>> can't isolate the outside (surround) sound from the > i >> nt >>> ended simulation, even with EAR foam plugs and audiometric insert phones. >>> VVMic and live recordings via Ambisonics is a solution to creating >>> "electric" listening in the real world. Again, I'm referring solely to CI >>> simulations. With the advent of electric-acoustic stimulation (EAS), more >>> than one mic is used per ear: One for the CI and a second for the HA. >>> Combinations of polar patterns can be created. Respective frequency >>> responses and processing can be sent to one or two ears (diotic and >>> dichotic situations). One caveat for using vocoding to mimic CIs is that >>> the acoustic simulation (and therefore stimulation) still necessitates a >>> traveling wave along the normal-hearing listener's basilar membrane. The >>> time it takes to establish a wave peak is not instantaneous (though >>> compressional waves in the the inner ear are virtually instantaneous), and >>> I believe a time-domain component to inner ear (mechanical) action can't >>> easily be excluded when using "acoustic" simulation of CIs. I suppose I >>> could look at data from BAERs and the Greenwood approximat i > o >> n >>> to account for the time-frequency interaction. Just some thinking... and >>> ideas to share with others interested in hearing impairments. >>> >>> >>> By the way, Teemko, if you're reading this, just wanted to let you know >>> that Bill Yost said he'd read your thesis over the weekend. I notice that >>> Bill and Larry Revit are in your references list. Larry isn't a fan of >>> Ambisonics--said to me in a phone communication that it sounds "tinny". I >>> suppose it does if one were to listen through laptop speakers or from poor >>> source material. Not sure what his source was. >>> -------------- next part -------------- >>> An HTML attachment was scrubbed... >>> URL: >>> <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121103/837528f1/attachment.html> >>> _______________________________________________ >>> 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 >> >> >> >> -- >> As of 1st October 2012, I have retired from the University, so this >> disclaimer is redundant.... >> >> >> These are my own views and may or may not be shared by my employer >> >> Dave Malham >> Ex-Music Research Centre >> Department of Music >> The University of York >> Heslington >> York YO10 5DD >> UK >> >> 'Ambisonics - Component Imaging for 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 > > > > -- > As of 1st October 2012, I have retired from the University, so this > disclaimer is redundant.... > > > These are my own views and may or may not be shared by my employer > > Dave Malham > Ex-Music Research Centre > Department of Music > The University of York > Heslington > York YO10 5DD > UK > > 'Ambisonics - Component Imaging for Audio' > > > ------------------------------ > > Message: 4 > Date: Tue, 6 Nov 2012 11:42:25 +0000 > From: Peter Lennox <p.len...@derby.ac.uk> > Subject: Re: [Sursound] Vestibular response, HRTF database, and now > with added height... > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: > > <28f33490c302424e98cc6dc2531b2048cd3d82e...@mkt-mbx01.university.ds.derby.ac.uk> > > Content-Type: text/plain; charset="us-ascii" > > Good point. > Do you think there may be an interaction with altered physiological states? - > I'm thinking alcohol might have a significant effect. Worth exploring, > anyhow... > Dr Peter Lennox > > School of Technology, > Faculty of Arts, Design and Technology > University of Derby, UK > e: p.len...@derby.ac.uk > t: 01332 593155 > ________________________________________ > From: sursound-boun...@music.vt.edu [sursound-boun...@music.vt.edu] On Behalf > Of Dave Malham [dave.mal...@york.ac.uk] > Sent: 06 November 2012 11:18 > To: Surround Sound discussion group > Subject: Re: [Sursound] Vestibular response, HRTF database, and now with > added height... > > And, of course, it would be essential to test for the effects of age > on the rapidity of change, so I guess I will be forced to come out of > retirement in order to provide a suitable subject without > inconveniencing anyone else... > > Dave > > On 6 November 2012 11:09, Peter Lennox <p.len...@derby.ac.uk> wrote: >> well, I think it's a big jump, so to speak to try to get funding for that. >> >> I have a much more modest proposal: >> >> Is auditory spatial perception and performance similar in all regions? - I >> have a strong suspicion that it's different in the Maldives. Further, I >> think it may be that, if you take someone that has been tested in, say, >> England, then transport them to the Maldives and test, looking for changes >> in performance over a 2 month period, one might find a progressive change. >> Then bring them back for a two month, repeating the test procedure. Then >> back to the Maldives, testing if the change in performance is similar, or >> indeed more rapid, the second time around. >> If significant results are obtained, we next try Bali. and so on. >> This will be much cheaper than the zero-G proposal >> >> In the interests of science, I am prepared to volunteer as a guinea pig, >> even if it means turning my back on my chances of being promoted to fourth >> assistant to the deputy office manager - that's how dedicated to science I >> am! >> Dr Peter Lennox >> >> School of Technology, >> Faculty of Arts, Design and Technology >> University of Derby, UK >> e: p.len...@derby.ac.uk >> t: 01332 593155 >> ________________________________________ >> From: sursound-boun...@music.vt.edu [sursound-boun...@music.vt.edu] On >> Behalf Of Dave Malham [dave.mal...@york.ac.uk] >> Sent: 05 November 2012 16:28 >> To: Surround Sound discussion group >> Subject: Re: [Sursound] Vestibular response, HRTF database, and now with >> added height... >> >> Hi Peter, >> Like I just said - needs experiments in zero G. I wonder what the >> acoustics in the ISS are like? Might be easier to organise decent >> acoustics in a Vomit Comet >> (http://en.wikipedia.org/wiki/Reduced_gravity_aircraft) especially as >> the padding already there would help. Now, where do we apply for >> funding?? >> >> Dave >> >> On 5 November 2012 14:18, Peter Lennox <p.len...@derby.ac.uk> wrote: >>> Eric, some interesting thoughts there, thanks. >>> One or two thoughts in reaction: >>> 1) you say " There have been a lot of studies regarding localization in the >>> transverse (horizontal) plane" - I know its quite common to conflate these, >>> but (as implied in your later thought experiment) - it's worth pointing out >>> that "horizontal" is specified as perpendicular to gravity. When a person >>> is standing or sitting straight, then if the head is not tilted then the >>> conflation is permissible. But. People tilt and move their heads all the >>> time, so acuity in hearing in the transverse plane is not the same as >>> acuity in the horizontal plane >>> >>> 2) Your question about acuity when the body is not in that 'usual' >>> orientation: I've thought the same thing, though the other way around - I >>> put people flat on their backs, then played ambisonic material tilted >>> through 90 degrees, to see if they got some different experience. So, I was >>> interested in perception in the vertical, but using that transverse plane. >>> The experience was different, but inconclusive in that it wasn't a >>> controlled experiment, of course. I found that identification of source >>> direction was less good than I'd anticipated. BUT - actually, (going back >>> to experiences whilst camping - I've lain awake in the countryside thinking >>> about these things) - listening (especially for direction) with your head >>> so close to the ground is certainly an unfamiliar experience. You've messed >>> up a lot of the pinnae effects. Interaural differences may well be >>> affected. You've got a peculiar pattern of very early reflections (from the >>> ground next to your ears). Most importantl y > , >> y >>> ou're listening to sources in the sky, with no reflective and occlusive >>> bodies around them. There's no 'ground effect' of the sort that a standing >>> or sitting person will get - that it, early reflected material that has >>> interacted with the ground, including filtering by surface features, >>> clutter (material objects and detritus have a tendency to be near the >>> ground due to gravity...) so, overall, hearing in that area just won't be >>> the same. >>> The above might partly account for why, in your experiment, hearing in the >>> horizontal might seem better than it ought - there are simply more cues >>> available for sources at or near the ground? However, in the camping >>> example, I did find increased instances of reversals. >>> >>> So I had thought there might be an interaction between gravity and spatial >>> hearing, but realised that some of it is just down to physics - the sky >>> really is different from the ground, we really are sort of "2.5 d" hearers >>> (and thinkers?). I'd also wondered whether distance(range) perception might >>> differ with direction. It does (items seem nearer), but more to do with the >>> physics of the matter - for sources in the sky, sometimes (not always!) >>> there is only a direct signal path. So, distance perception as the product >>> of the direct/indirect ratio doesn't seem quite the right formulation. >>> >>> These things need some decent experimentation, it seems to me >>> >>> Cheers >>> ppl >>> >>> >>> Dr. Peter Lennox >>> >>> School of Technology, >>> Faculty of Arts, Design and Technology >>> University of Derby, UK >>> e: p.len...@derby.ac.uk >>> t: 01332 593155 >>> >>> -----Original Message----- >>> From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu] >>> On Behalf Of Eric Carmichel >>> Sent: 03 November 2012 18:54 >>> To: sursound@music.vt.edu >>> Subject: [Sursound] Vestibular response, HRTF database, and more >>> >>> Greetings, >>> Mostly through serendipity, I have had the pleasure and privilege of great >>> teachers. I studied recording arts under Andy Seagle (andyseagle.com) who >>> recorded Paul McCartney, Hall & Oats, and numerous others. My doc committee >>> included Bill Yost, who is widely known among the spatial hearing folks. >>> And, of course, I've learned a lot about Ambisonics from people on this >>> list as well as a plethora of technical articles. >>> >>> I recently sent an email to Bill with the following question/scenario. I >>> thought others might wish to give this thought, too, as it gets into HRTFs. >>> >>> There have been a lot of studies regarding localization in the transverse >>> (horizontal) plane. We also know from experiments how well (or poorly) we >>> can localize sound in the frontal and sagittal planes. By simply tilting >>> someone back 90 degrees, his/her ears shift to another plane. This is >>> different from shifting the loudspeaker arrangement to another plane >>> because the semicircular canals are now in a different orientation. If a >>> circular speaker array was setup in the coronal plane and the person was >>> lying down, then his/her ears would be oriented in such a way that the >>> speakers now circle the head in the same fashion as they would in the >>> horizontal plane when the person is seated or standing. It's a "static" >>> vestibular change, and gravity acting on the semicircular canals (and body) >>> lets us know which way is up. But do we have the same ability to localize >>> when the body is positioned in different orientations, even when the >>> sources "follow" the orientation (as is the cas e >> in >>> the above example)? How about localization in low-g environments (e.g. >>> space docking)? The question came to me while camping. I seem able to >>> pinpoint sounds quite well in the (normal) horizontal plane despite a >>> skewed HRTF while lying down (and somewhat above ground). >>> >>> On another (but related) topic, I have downloaded the HRTF data from the >>> Listen Project, and have been sorting the participant's morphological >>> features. I have this in an Excel spreadsheet, and am converting this to an >>> Access database. Using the data, one can pick an "appropriate" HRTF >>> starting with gross anatomical features (such as headsize) and whittle it >>> down to minute features (such as concha depth or angle). I find HRTF >>> discussions interesting, but still argue that headphones and whole-body >>> transfer functions make a difference, too. Insert phones destroy canal >>> resonance, whereas an earcup with active drivers may have a large >>> "equivalent" volume, thus minimizing external meatus/earcup interaction (a >>> mix and match of resonances). Because of this, there can be no ideal HRTF, >>> even when it matches the listener. >>> >>> While listening to HRTF demos, the notion of auditory streaming and >>> auditory scenes came to mind. Some sounds were externalized, but other >>> sounds of varying frequencies, while emanating from the same sound source, >>> appeared in my head. The end result was that the externalized sounds >>> provided a convincing (or at least fun) illusion, but problems do persist. >>> A stringent evaluation of HRTF / binaural listening via headphones would >>> require breaking the sounds into bands and seeing if a sound's constituent >>> components remain outside of the head. When doing so, a brick-wall filter >>> wouldn't be necessary, but a filter that maintains phase coherency would be >>> recommended. The demo I refer to was that of a helicopter flying overhead. >>> Though I haven't done this (yet), it would be interesting to use FFT >>> filtering to isolate the turbine whine (a high-pitched sound) from the >>> chopper's blades. The high-pitched sound appeared to be in my head, whereas >>> the helicopter as a whole seemed exter n > a >> li >>> zed. Again, an individualized HRTF and different phones may yield different >>> results. Side note: Be careful using FFT filtering--it can yield some >>> peculiar artifacts. >>> >>> I am hoping to use headtracking in conjunction with VVMic to model >>> different hearing aid and cochlear implant mics in space. This offers the >>> advantage of presenting real-world listening environments via live >>> recordings to study/demonstrate differences in mic polar patterns (at least >>> first-order patterns) and processing without the need for a surround >>> loudspeaker system. In fact, it's ideal for CI simulations because an >>> actual CI user never gets a pressure at the eardrum that then travels along >>> the basilar membrane, ultimately converted to nerve impulses. With VVMic >>> and HRTF data, I should be able to provide simulations of mics located on a >>> listener's head and then direct the output to one or both ears. This does >>> not represent spatial listening, but it does represent electric (CI) >>> hearing in space. Putting a normal-hearing listener in a surround sound >>> environment with mock processors and real mics doesn't work because you >>> can't isolate the outside (surround) sound from the > i >> nt >>> ended simulation, even with EAR foam plugs and audiometric insert phones. >>> VVMic and live recordings via Ambisonics is a solution to creating >>> "electric" listening in the real world. Again, I'm referring solely to CI >>> simulations. With the advent of electric-acoustic stimulation (EAS), more >>> than one mic is used per ear: One for the CI and a second for the HA. >>> Combinations of polar patterns can be created. Respective frequency >>> responses and processing can be sent to one or two ears (diotic and >>> dichotic situations). One caveat for using vocoding to mimic CIs is that >>> the acoustic simulation (and therefore stimulation) still necessitates a >>> traveling wave along the normal-hearing listener's basilar membrane. The >>> time it takes to establish a wave peak is not instantaneous (though >>> compressional waves in the the inner ear are virtually instantaneous), and >>> I believe a time-domain component to inner ear (mechanical) action can't >>> easily be excluded when using "acoustic" simulation of CIs. I suppose I >>> could look at data from BAERs and the Greenwood approximat i > o >> n >>> to account for the time-frequency interaction. Just some thinking... and >>> ideas to share with others interested in hearing impairments. >>> >>> >>> By the way, Teemko, if you're reading this, just wanted to let you know >>> that Bill Yost said he'd read your thesis over the weekend. I notice that >>> Bill and Larry Revit are in your references list. Larry isn't a fan of >>> Ambisonics--said to me in a phone communication that it sounds "tinny". I >>> suppose it does if one were to listen through laptop speakers or from poor >>> source material. Not sure what his source was. >>> -------------- next part -------------- >>> An HTML attachment was scrubbed... >>> URL: >>> <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121103/837528f1/attachment.html> >>> _______________________________________________ >>> 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 >> >> >> >> -- >> As of 1st October 2012, I have retired from the University, so this >> disclaimer is redundant.... >> >> >> These are my own views and may or may not be shared by my employer >> >> Dave Malham >> Ex-Music Research Centre >> Department of Music >> The University of York >> Heslington >> York YO10 5DD >> UK >> >> 'Ambisonics - Component Imaging for 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 > > > > -- > As of 1st October 2012, I have retired from the University, so this > disclaimer is redundant.... > > > These are my own views and may or may not be shared by my employer > > Dave Malham > Ex-Music Research Centre > Department of Music > The University of York > Heslington > York YO10 5DD > UK > > 'Ambisonics - Component Imaging for 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 > > > End of Sursound Digest, Vol 52, Issue 6 > *************************************** _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
