Identification of multidimensional complex sounds having parallel dimension structure.

The present series of experiments examined the ability of normal-hearing listeners to make use of cues from multiple, independent stimulus dimensions when classifying multidimensional complex sounds. Ten listeners classified complex sound pulses that differed along three independent dimensions. The stimuli were 100 ms in duration and were synthesized using five simultaneous sinusoids. The three dimensions of the complex stimuli manipulated in this experiment were harmonicity, spectral shape, and amplitude envelope. Each stimulus dimension could take on one of two values, referred to here as target or nontarget. Eight stimuli were synthesized using all possible combinations of the dimension values. Subjects were trained to label two stimuli, the two having either all-target or all-nontarget values, as "+" and "0," respectively. Following this training, subjects were asked to classify all eight stimuli as either "+" or "0." Results of this experiment indicated that listeners preferred to classify these stimuli on the basis of one stimulus dimension. However, the preferred dimension was not the same for all of the listeners. In addition, it was demonstrated that it was possible to train an individual to use a dimension other than the one or two initially preferred when classifying the stimuli.