Sek A, Moore B C
Department of Experimental Psychology, University of Cambridge, England.
J Acoust Soc Am. 1994 Jun;95(6):3511-7. doi: 10.1121/1.409968.
This article is concerned with the mechanisms underlying the detection of amplitude modulation (AM), frequency modulation (FM), and mixed modulation (MM), i.e., simultaneously occurring AM and FM. In a previous study [B. C. J. Moore and A. Sek, J. Acoust. Soc. Am. 92, 3119-3131 (1992)], psychometric functions were measured for the detection of AM alone and FM alone, using a 10-Hz sinusoidal modulator and a 1-kHz carrier frequency. Detectability was then measured for combined AM and FM, with modulation depths selected so that each type of modulation would be equally detectable if presented alone. The detectability of the MM was better than would be predicted if the two types of modulation were coded completely independently. This study examined the possibility that the good detectability of MM was caused by the fact that the AM and the FM were correlated, so that each was predictable from the other. The design was similar to that of our earlier study, but the 10-Hz sinusoidal modulator was replaced by a narrow-band noise modulator. In the MM conditions, the modulators for AM and FM were either strongly positively correlated or essentially uncorrelated. In experiment 1, the waveforms of the noise modulators were fixed throughout the experiment (frozen noise). In experiment 2, the waveforms of the noise modulators were chosen independently for each trial. In both experiments, for both correlated and uncorrelated modulators, the detectability of the MM was better than would be predicted if the two types of modulation were coded completely independently.(ABSTRACT TRUNCATED AT 250 WORDS)
本文关注幅度调制（AM）、频率调制（FM）以及混合调制（MM，即同时出现的AM和FM）检测背后的机制。在之前的一项研究中[B. C. J. 摩尔和A. 塞克，《美国声学学会杂志》92, 3119 - 3131 (1992)]，使用10赫兹的正弦调制器和1千赫兹的载波频率，测量了单独检测AM和单独检测FM时的心理测量函数。然后测量了AM和FM组合的可检测性，选择调制深度以便如果单独呈现每种调制类型时它们的可检测性相同。MM的可检测性比如果两种调制类型完全独立编码时所预测的要好。本研究考察了MM良好可检测性是由AM和FM相关这一事实导致的可能性，即每种调制都可从另一种调制预测得出。实验设计与我们早期的研究相似，但10赫兹的正弦调制器被窄带噪声调制器所取代。在MM条件下，AM和FM的调制器要么高度正相关，要么基本不相关。在实验1中，噪声调制器的波形在整个实验过程中是固定的（冻结噪声）。在实验2中，每次试验独立选择噪声调制器的波形。在两个实验中，对于相关和不相关的调制器，MM的可检测性都比如果两种调制类型完全独立编码时所预测的要好。（摘要截选至250词）
