Dai H, Green D M
Department of Psychology, University of Florida, Gainesville 32611.
J Acoust Soc Am. 1992 May;91(5):2845-54. doi: 10.1121/1.402965.
This study measures the ability of observers to compare the intensities of two stimuli occupying different frequency regions. It includes three experiments, each experiment having two conditions. In one condition, the two stimuli to be compared were presented simultaneously within each interval; this condition has been called profile analysis. In the other condition, the two stimuli were presented successively within each interval. Because the overall level of the stimuli was randomized between intervals, the observers were encouraged to compare the intensities of the two stimuli within each observation interval rather than between intervals. The stimuli were two simple tones in experiment 1 and two tonal complexes in both experiments 2 and 3. The stimuli used in experiments 2 and 3 differed in frequency. The results show that simultaneous comparisons are superior to successive comparisons. For simple tones, the difference in threshold is about 8 dB; for complexes with 10 to 11 components, the difference in threshold is about 15 dB. These differences can be explained by assuming that internal noises in different channels were partially correlated when stimuli in those channels were presented simultaneously and were independent when the stimuli were presented successively. Cancellation of the correlated noise is therefore possible with simultaneous comparisons, making such discrimination better than that achievable with successive comparisons.
本研究测量了观察者比较占据不同频率区域的两种刺激强度的能力。它包括三个实验，每个实验有两种条件。在一种条件下，要比较的两种刺激在每个间隔内同时呈现；这种条件被称为轮廓分析。在另一种条件下，两种刺激在每个间隔内相继呈现。由于刺激的总体水平在不同间隔之间是随机的，所以鼓励观察者在每个观察间隔内比较两种刺激的强度，而不是在不同间隔之间进行比较。实验1中的刺激是两个纯音，实验2和实验3中的刺激都是两个音调复合体。实验2和实验3中使用的刺激在频率上有所不同。结果表明，同时比较优于相继比较。对于纯音，阈值差异约为8分贝；对于具有10到11个成分的复合体，阈值差异约为15分贝。这些差异可以通过以下假设来解释：当那些通道中的刺激同时呈现时，不同通道中的内部噪声部分相关，而当刺激相继呈现时，内部噪声是独立的。因此，通过同时比较可以消除相关噪声，使得这种辨别比相继比较所能达到的更好。
