Critical ratio for tones, modulated tones and noise, and speech

The critical ratio (CR) is a very basic concept first introduced in 1930 [Fletcher and Munson, (1933)], but rarely studied today. In this study we have remeasured the CR for a host of signals, including long duration tones, AM modulated tones at various modulation depths, at 3 Hz modulation, at several levels, modulated noise at two modulation depths levels, and speech signals of several bandwidths. A simple peak detection model explains most of the data. Some subject differences are also of interest.