On distance perception: I don't know if it's still available, but Pavel Zahorik had a paper reviewing auditory distance perception some years ago. As has been said here, Doppler, whatever else it is, isn't really a distance cue.
I'd say the 'potential cues' and the 'actual cues' used in any given situation, and the perceptual weighting of cues in particular circumstances, varies so much that distance perception - and change-of-distance perception, are far more complex lab problems than direction, yet, oddly, are probably more perceptually significant 'in the wild'. I have a hunch that 'ground effect' (where most physical detritus accumulates, due to gravity!) is under-explored in this context. That is, in real environments, the higher the frequency the more scattering takes place, with increased distance (range) - that's simply the physics of wavelength and obstacle sizes. The effects of multiple signal paths at higher frequencies are readily discernible, and especially, changes in this. In fact, as a distance(range) cue, we could actually group this into a phenomenon of measurable components that could be psychophysically tested. If anyone knows of work in this area, I'd be grateful. People often talk about direct/indirect ratio - bit like dry/reverb ratio, but actually, that makes it sound like a straightforward energy comparison; that doesn't seem quite right - indeed, often, at a broad range of frequencies, it's all indirect. So then you'd have to talk about "most direct/less direct", which doesn't seem at all precise. The spectra consequences of multiple signal paths - and changes of those due to object movement (in relation to reflective and occlusive features in the environment) might offer physically-robust range cues to perception, or at least change-of-range cues - I've previously called this "comingness" - not just to annoy audio engineers (that's just a bonus!) but we might call it 'auditory looming' just as we refer to 'visual looming' - but we really need to keep in touch with the point that one of the most important apperceptions one might have to be skilled in is in understanding "things-quite-near-me-and-getting-nearer-rapidly" regards 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 ________________________________________ From: sursound-boun...@music.vt.edu [sursound-boun...@music.vt.edu] On Behalf Of Eric Carmichel [e...@elcaudio.com] Sent: 25 February 2013 01:37 To: Surround Sound discussion group Subject: Re: [Sursound] Saga of the Subs Hello Robert, Perception of distance is a complex interaction, and psychoacoustical experiments generally limit the number of variables (out of necessity) studied in static or laboratory settings. Not that I disagree with you, but there's more to the "Doppler Illusion" (as it has been called) than meets the eye... er, the ear. For two related papers, please refer to the following links: http://www.public.asu.edu/~mmcbeath/mcbeath.research/Doppler/Doppler.html http://psychology.clas.asu.edu/files/1996_JEP-HPP%28DopplerIllusion%29.pdf I did something similar while an undergrad, but did have enough confidence in my own measurements to submit the findings for publication. Most of what I realized is that a measurable change in pitch seemed too small for anyone but a trained musician to perceive it, yet everyone could judge the object as approaching and then receding. The spectral nature of the moving vehicle changed, but mostly due to relative proximity of buildings and obstacles and diffraction. But the fundamental pitch of, say, a siren, when isolated, didn't provide the dominant cue. I guess it's akin to the duplex theory of localization: We use the cues that are available; there's not an instant switch between one mode to the next, particularly when complex sounds interact with the head and pinnae, and head movements also help resolve ambiguities. Vision and experience naturally add to our perception of distance and motion. Thanks for corrections, but please also consider viewing the above two links--I need to re-read them myself. Best, Eric ________________________________ From: Robert Greene <gre...@math.ucla.edu> To: Eric Carmichel <e...@elcaudio.com>; Surround Sound discussion group <sursound@music.vt.edu> Sent: Sunday, February 24, 2013 5:46 PM Subject: Re: [Sursound] Saga of the Subs This is wrong about the Doppler effect and perception of distance. It would be correct if the object moving and emitting sound as it moved were coming straight towards you and going through you and then moving away. But a police car with a siren say is not aiming straight at you(or at least you better hope not!) It is going by on a straight line that has a closest point to you but that closest point is not you! So the amount of pitch shift in fact changes continuously, being a max shift up when the car is far away, diminishing gradually until the car is as close to you as it will get(at which point the car is not changing distance from you at all in the instantaneous sense) and then gradually as the object moves away with increasing speed relative to you! the pitch falls to a minimum. This is not dependent on mel shifting with level--it is literally the case on the frequency level. (The mel shift would be the same whether the car were approaching or departing-- just reversed in time. This as I recall is not what is observed-- the situation does not have time reversal symmetry) Robert -------------- next part -------------- An HTML attachment was scrubbed... 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