Sources of variation in profile analysis. II. Component spacing, dynamic changes, and roving level.
Profile-analysis experiments have typically employed static profiles with constant frequency components spaced at equal intervals along a logarithmic frequency axis. Most periodic, naturally occurring stimuli, however, have components that are harmonically related and vary dynamically in time. One goal of these studies was to determine whether amplitude-increment detection thresholds are different in dynamic, harmonically spaced profiles compared to those for static-log profiles, and why such differences might exist. A second goal was to determine the impact of roving levels (within-trial variation of level). Thresholds for static-log profiles were, on average, 8.7 dB lower than for static-harmonic profiles. A traditional filter-bank model could not account for this result. No consistent effect of dynamic contour (an exponential rising frequency glide) was observed. Thresholds were consistently poorer by 4 to 7 dB when the level was roved, but the differences in thresholds among the different profiles varied little. It is proposed that the higher thresholds observed in static-harmonic profiles may be accounted for by the more intense pitch strength associated with the harmonic profiles.
Drennan
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Department of Speech and Hearing Sciences, Indiana University, Bloomington 47406, USA. warddrennan@yahoo.com
Watson
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D000293:Adolescent; D000328:Adult; D001288:Attention; D001307:Auditory Perception; D005260:Female; D006801:Humans; D008297:Male; D010897:Pitch Discrimination; D011571:Psychoacoustics; D012016:Reference Values; D013018:Sound Spectrography