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BAD MSG: whom I've not yet been in touch), it seems that profile nalysis has only been systematically studied up to about 1 frequency component per CB? For instance, in Green, D.M. (1992). "The number of components in profile analysis tasks," J. Acoust. Soc. Am. 91, pp. 1616-1623 one finds that most of the work was on up to 21 (and sometimes 24) log-spaced components in a [200,5000] Hz interval, supplemented by just two points at 41 and 81 components (his Fig. 1). In my experience, a lot more than mere masking seems to be happening when stepping from 41 through 81 components on a log scale (where my default interval is [500,5000] Hz to get a fair time-frequency compromise in case of dynamic profiles - although I'm in this posting referring only to static profiles). Not only does tonality appear to decrease as one would expect, but beyond, say, 70 or so components an unpleasant roughness becomes rather prominent, and going to, say, 120 components sounds pretty bad to me. Now I can imagine that this roughness can be explained from intra-CB beats as one moves beyond the 1 component per CB density. However, shouldn't this intra-CB beating also have significant effects on profile discrimination thresholds? Shouldn't this give strong dependencies, and possibly more structure (maybe even minima an maxima) than just a simple rising slope, for change detection threshold as a function of the number of frequency components as one moves in small increments from about 1 component per CB up to say 3 or 4 components per CB? In principle I can imagine that the beating could help to (learn to) perceive intensity changes in individual components, because the beating changes with the intensities of components within a single CB. Normally one would want to separate the effects of beating from other frequency detection effects for the sake of auditory research (the notched-noise methods being based on such considerations). In my quest it is the other way around: in the end I don't really care what mixture of effects is used in hearing as long as it gives maximum detectability of profile changes (though I love to understand things like everybody else). If intra-CB beats can help that's fine. Currently I use about three components per CB, and would like to learn more about profile analysis research around that density range. Have these things been systematically explored somewhere in the context of profile analysis? Basically I'd like to see more points in Fig. 1 of Green's interesting 1992 paper in the range between m=41 and m=81 sinusoids, and to see an additional axis (nice 3D plot!?) showing the threshold changes with training time.

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DAn Ellis <dpwe@ee.columbia.edu>
Electrical Engineering Dept., Columbia University