Sek A, Moore B C
Department of Experimental Psychology, University of Cambridge, England.
J Acoust Soc Am. 1996 Oct;100(4 Pt 1):2332-40. doi: 10.1121/1.417942.
These experiments examined the ability of subjects to detect auditory "events" composed of a brief modulation in the temporal center of an otherwise steady sinusoid. In experiment 1, psychometric fluctuations were measured for detecting either amplitude modulation (AM) or frequency modulation (FM) composed of a single cycle of a raised-cosine function (either positive going or negative going); the modulation frequency was 10 Hz, so the event lasted for 100 ms. Then, psychometric functions were measured for stimuli with both AM and FM, using pairs of values of AM and FM that were equally detectable; pairs were always modulated in the same direction, so a positive amplitude excursion went together with a positive frequency excursion. Performance was compared with the "reference" detectability that would be predicted from the optimal combination of independent sources of information. When the AM and FM were synchronous, detectability was better than the reference detectability. When the FM was delayed by 100 ms relative to the AM, detectability was mostly equal to or less than the reference detectability. The better performance with synchronous AM and FM is consistent with an explanation based on an excitation-pattern model. Experiment 2 was similar to experiment 1, except that the event was a single cycle of sinusoidal modulation starting at 0 degree phase or 180 degrees phase. When the AM and FM were synchronous and in phase, detectability was better than the reference detectability. When the AM was delayed by 200 ms relative to the FM or had opposite starting phase, detectability was close to or below the reference detectability. However, for the case where the delay was 100 ms and the modulation had the same starting phase for AM and FM, detectability was better than the reference detectability. A control experiment using two successive cycles of either AM or FM showed a similar, but slightly smaller, effect. It appears that detectability can be enhanced when two successive events form a regular temporal pattern.
这些实验研究了受试者检测由稳定正弦波的时间中心处的短暂调制组成的听觉“事件”的能力。在实验1中，测量了检测由单个余弦函数周期（正向或负向）组成的幅度调制（AM）或频率调制（FM）时的心理测量波动；调制频率为10Hz，因此该事件持续100ms。然后，使用同等可检测的AM和FM值对来测量具有AM和FM的刺激的心理测量函数；对总是在相同方向上调制，因此正幅度偏移与正频率偏移同时出现。将性能与从独立信息源的最佳组合预测的“参考”可检测性进行比较。当AM和FM同步时，可检测性优于参考可检测性。当FM相对于AM延迟100ms时，可检测性大多等于或小于参考可检测性。同步AM和FM时更好的性能与基于兴奋模式模型的解释一致。实验2与实验1类似，不同之处在于该事件是从0度相位或180度相位开始的单个正弦调制周期。当AM和FM同步且同相时，可检测性优于参考可检测性。当AM相对于FM延迟200ms或具有相反的起始相位时，可检测性接近或低于参考可检测性。然而，对于延迟为100ms且AM和FM具有相同起始相位的情况，可检测性优于参考可检测性。使用AM或FM的两个连续周期的对照实验显示了类似但稍小的效果。似乎当两个连续事件形成规则的时间模式时，可检测性可以提高。
