Modulation masking phenomenon for masking signals of different spectral and statistical properties

Modulation masking effect for modulation maskers of different spectral and statistical
properties was investigated in this study. Three noisebands centred at 16 Hz were used as
modulation maskers, namely: 1) 32-Hz wide Gaussian noise (GN 32 Hz); 2) 32-Hz wide lownoise
noise (LNN 32 Hz) and 3) 4-Hz wide low-noise noise (LNN 4 Hz). The GN 32 Hz and
LNN 32 Hz were characterized by the same power spectrum density and different probability
density functions. Conversely, the LNN 32 Hz and LNN 4 Hz had the same probability
density functions, but different power spectrum densities. The root mean square of the modulation
maskers was normalized to 0.2. During the measurements audibility of a sinusoidal
probe modulation presented simultaneously with the modulation maskers was investigated by
means of the 3AFC adaptive procedure with a 3-down/1-up decision rule. The results of the
experiment indicated that modulation masking was mainly determined by power density spectrum
of the modulation masker, however, due to peripheral compression, temporal (statistical)
properties of the masker might have played also some role in the modulation masking.