Subject: Re: reverse engineering of acoustic sources From: John Neuhoff <jneuhoff(at)WOOSTER.EDU> Date: Sat, 31 Jan 2004 11:11:04 -0500There is also some evidence that human listeners have a limited ability to identify the shape (and a few other physical characteristics) of a vibrating object. However, it is still unclear exactly what acoustic characteristics the listeners use. See: Lakatos, S., McAdams, S., & Causse, R. (1997). The representation of auditory source characteristics: Simple geometric form. Perception & Psychophysics, 59(8), 1180-1190. Carello, C., Anderson, K. L., & Kunkler-Peck, A. J. (1998). Perception of object length by sound. Psychological Science, 9(3), 211-214. Kunkler-Peck, A. J., & Turvey, M. T. (2000). Hearing shape. Journal of Experimental Psychology: Human Perception & Performance, 26(1), 279-294. Lutfi, R. A. (2001). Auditory detection of hollowness. J Acoust Soc Am, 110(2), 1010-1019. Grassi, M., (2002). Recognising the size of objects from sounds with manipulated acoustical parameters. In: Da Silva, J. A., Matsushima, E. H. & Ribeiro-Filho, N, P. (eds.), Fechner Day 2002. Proceedings of the 18th Annual Meeting of the International Society for Psychophysics. Rio de Janeiro, Brasil: The International Society for Psychophysics, 392-397. -John ________________________________ John G. Neuhoff Department of Psychology The College of Wooster Wooster, OH 44691 Phone: 330-263-2475 Fax: 928-244-5577 http://jneuhoff.com ************************ "Ecological Psychoacoustics" from Academic Press June, 2004 http://www.jneuhoff.com/ecopsyc.htm ************************************ > -----Original Message----- > From: AUDITORY Research in Auditory Perception > [mailto:AUDITORY(at)LISTS.MCGILL.CA] On Behalf Of Georg Essl > Sent: Saturday, January 31, 2004 7:54 AM > To: AUDITORY(at)LISTS.MCGILL.CA > Subject: Re: reverse engineering of acoustic sources > > > Hi Jim, > > I cannot speak to the claims about the universe and I have > yet to get hold > of this article. But regarding the problem of determining the > shape of a > vibrating structure from its spectrum: This has a sizeable > literature in > mathematics and many currently active contributers to it. > > A very recent but also very technical review is being written by Steve > Zelditch of JHU and available online at: > > http://mathnt.mat.jhu.edu/zelditch/Preprints/SurveyJDGAMS4.pdf > > a brief and somewhat more readable survey by Ivana Alexandrava can be > found here: > > http://math.berkeley.edu/~alanw/240papers00/alexandrova.pdf > > Unfortunately I know of very little writing in this field that is less > reliant on the language, background and notation of contemporary pure > mathematics (if anybody knows good "descriptive" surveys, I'd > love to hear > about it!) > > Since Carolyn Gordon and coworkers gave explicit > constructions of "drums > that sound the same" it is known that in general the inverse > doesn't hold > in the 2-D case. But the constructions that are used are based on > triangles and hence don't have a smooth boundary. The question of the > concave smooth contour is still unsolved though Zelditch, who > wrote the > above survey, recently reported some result in this direction. However > even a shape like a guitar top plate is not yet solved, as Zelditch's > proofs require that what mathematicians call the "length > spectrum" (the > set of lengths of closed dynamic trajectories on the > geometry) only have > non-degenerate lengths which keeps his results from being much more > general. > > It's noteworthy, that even the forward spectral result from > geometry is > not generally solved or exhibits symptoms that illustrate the > difficulty > of the forward and the inverse problem. E.g the stadium billiard (two > semi-circles connected by straight lines) as representing the > dynamics of > a membrane of that shape has chaotic dynamics. I highly recommend the > beautiful paper by Michael Berry on the dynamical result with > respect to > chaos of deforming a circle into a stadium: > http://www.phy.bris.ac.uk/research/theory/Berry/the_papers/Berry102.pdf But to go back to the paragraph at hand, with the caveat of not knowing the context of the paragraph in their article, at least with respect to acoustics there is still a lot not known precisely. - Georg georg(at)mle.media.mit.edu (current) > Date: Fri, 30 Jan 2004 14:24:03 -0600 > From: beauchamp james w <jwbeauch(at)UX1.CSO.UIUC.EDU> > Subject: reverse engineering of acoustic sources > > In the Februrary, 2004 issue of Scientific American, Wayne Hu and > Martin White in their article "The Cosmic Symphony" write > > "...researchers have been able to use [temperature variations of > the cosmic microwave background] to precisely estimate the age, > composition and geometry of the universe. The process is analogous > to determining the construction of a musical instrument by > carefully listening to its notes." > > My question is: Has there been any work in the second area? (I know > the reverse has been worked on.) Are the authors trying to say that > the cosmic quest is as difficult as the acoustic one, or as easy? > > Jim Beauchamp > Univ. of Illinois Urbana-Champaign > > PS I note that in their p. 48 figure they have the wrong series of > acoustic standing waves.