Threshold fine structure affects amplitude modulation perception

Abstract

Modulation detection thresholds of a sinusoidally amplitude-modulated tone were measured for two different positions of the low-level carrier relative to the fine structure of the threshold in quiet. Modulation detection thresholds were higher for a carrier at a fine-structure minimum than for a carrier at a fine-structure maximum, regardless of whether the carriers had the same sound pressure level or the same sensation level. This indicates that even for small variations of the carrier frequency, the sensitivity to amplitude modulation can vary substantially due to the frequency characteristics of the threshold in quiet.