Modulation detection interference with two-component masker modulators

Thresholds were measured for detecting amplitude modulation of a single tonal carrier in the presence of modulated maskers. The masker modulator contained either one or two sinusoidal components. As found in previous studies, there was a detrimental effect of masker modulation on the detection of probe modulation. Interference was obtained with a 4-Hz separation between the two components of the masker modulator with the probe modulated at the 4-Hz beat rate. The amount of interference obtained with the two-component masker modulator was greater than that produced by the individual components of the masker modulator. The amount of interference increased with the depth of the masker-modulator beating and the number of masker carriers. The interference due to beating of the masker-modulator components was reduced when the beat rate was increased from 4 to 10 Hz. Results obtained with two-component masker modulators indicate a masking effect not predicted by a spectral representation of the probe and masker envelopes.