Abstract:
The aim of this study was to evaluate the resultant value of the modulation depth perceived binaurally when sinusoidally amplitude-modulated tones, with different modulation depths, were presented to the left and right ear. Different values of the modulation index (ranging from 0% to 100%), modulation frequency (4, 64, 128 Hz), and carrier frequency (250, 1000, 4000 Hz) were used in the experiment. The data show that for low values of the modulation indexes, the dichotic perception of modulation depth approximates the arithmetic mean of the indexes presented to the left and right ear. However, this is not the case for higher values of the modulation index for which the perceived modulation depth is always lower than the mean of the indexes at both ears. Additionally, it was stated that perceived modulation depth does not depend on the rate of modulation for relatively small interaural differences in modulation indexes. In turn, for larger interaural differences the perceived modulation depth tends to decrease with increasing modulation rate. The model of binaural perception of AM tones is considered. [sup a)]Permanent address: Institute of Acoustics Adam Mickiewicz University, Poznan ul. Matejki 48/49, Poland.