Adelbert W. Bronkhorst
TNO Inst. for Perception, P. O. Box 23, 3769 ZG Soesterberg, The Netherlands
In this study on energy profile discrimination, the basic sound consists of five Gaussian-shaped tone pulses (wavelets). The choice of the timing and the frequencies of the individual wavelets is such that they are always arranged in a linear array in the log(f)-t spectrogram, with the orientation of the array as an important parameter (horizontal, vertical or any oblique orientation). An additional parameter of these five-wavelets arrays is the mutual separation between the wavelets. For a given orientation and separation, the reference sound contains all five wavelets with equal energy, while in the target sound the (relative) energy of the middle wavelet is reduced: The just-detectable decrement of the middle wavelet is determined with a standard adaptive 2AFC procedure, including a roving-level paradigm. This form of profile analysis with the present five-wavelets arrays shows that (1) the performance is better with a purely temporal pattern (horizontal array) than with a purely spectral pattern (vertical array), and (2) for some specific oblique orientations of the array the performance is extremely poor, with just-detectable decrements of the middle wavelet of the order of 20 dB.