Previous research suggests that the temporal pattern of dissimilar sounds may be a basis for confusion. To extend this research, the present study used complex sounds formed by simultaneously playing components drawn from four sound categories. Four temporal patterns, determined by sound duration and duty cycle were also used, producing a total of 16 basic components. The density (i.e., number of components played simultaneously) ranged from one to four. Subjects heard a sequence of two complex sounds and judged whether they were same of different. For trials in which the sounds differed, there were three possible manipulations: the addition of a component, the deletion of a component, and the substitution of one component for another. Overall accuracy was 94 percent across the 144 dissimilar sound complexes. As density increased, a significantly greater number of errors occurred for all classes of manipulations. Changes in individual temporal patterns across a variety of manipulations of sounds involving adding, deleting and substituting components were accurately discriminated. Subjects were least accurate in detecting substitutions of a pattern. A single sound category was identified in error prone sequences which was most often involved as the changing component from first to second sound presentation. Suggestions for the design of easily discriminated sounds are discussed.
Loudness of complex sounds as a function of the standard stimulus and the number of components
