Subject: Re: Auditory wheel From: Al Bregman <al.bregman@xxxxxxxx> Date: Thu, 18 Mar 2010 20:48:13 -0500 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>Hi Michael, The "Shepard Tone" ascending sequence is inherently a loop, in the sense that after it ascends an (apparent) octave, it is acoustically back where it started. If you want a more continuous stimulus, Jean-Claude Risset has created a continuous version. - Al Bregman On Thu, Mar 18, 2010 at 5:22 PM, Michael H. Coen <mhcoen@xxxxxxxx> wrote: > Hello list, > > We are all familiar with the notion of a visual color wheel, e.g., a > continuous, circular representation of colors in some color space such > as HSV. (Here's a wikipedia page with some visual examples: > http://en.wikipedia.org/wiki/Color_wheel) > > Of course, there are many different color wheels, given that there are > many different color spaces in which to model them. > > I'm looking for the auditory equivalent of a color wheel. Namely, a > parametrized, continuous method for generating a series of sounds that > form a "perceptual loop" that has no perceived gaps. > > I've coded a several of these, e.g., a violin morphing into a piano > morphing into a clarinet, which then morphs back into a violin. They > are all playing middle C and the ASDR envelopes for the generated, > equal-length samples are identical. > > I'm doing this to measure discriminative acuity in distinguishing sounds > along the auditory wheel, as part of a larger multimodal perceptual > experiment. > > However, what I've found is that people with musical backgrounds have > far greater discriminatory power in separating nearby sounds than those > who have little training. There are also "unintended" clues, such as > harmonic complexity, which people appear differentially sensitive to. > > Thus, I wonder if there is any work in creating such an auditory wheel > that might be expected to reduce bias due to background and/or culture. > E.g., using a heptatonic music scale may not be a good idea and sounds > derived from familiar instruments are probably best avoided as well. I > would like participants to be on an equal auditory footing, so to speak. > I'll repeat that it is essential that there be a "loop" in the sound > presentation that is not due to a simple repetition of sounds, e.g., a > sine wave rising and then falling in frequency would not be useful. > > Any pointers, suggestions, code, etc., would be most welcome. > > Best, > Michael Coen > --