Binaural unmasking of the periodic component in the envelope of an amplitude-modulated signal

A binaural unmasking of a tone component that is present in an amplitude-time noise envelope of a high-frequency signal is studied. The signal has the form of a sinusoidal carrier of frequency 2000–5000 Hz amplitude modulated by a low-frequency signal. The modulating function is a mixture of a 300-Hz tone (interaurally inphase or antiphase) and a dichotic masking noise within 0–400 Hz, this mixture being subjected to a half-wave linear rectification. The listener has to detect the rhythmic component in the modulating noise function. It is shown that, under the aforementioned conditions, the binaural difference in masking levels grows up to 25 dB with increasing carrier frequency but drastically decreases in the case of a masking of the low-frequency part of the basilar membrane in the vicinity of 300 Hz. The lateralization based on the interaural phase of a 100% amplitude modulation by a 300-Hz tone at a carrier frequency within 2000 to 5000 Hz also drastically decreases (in our experiments) when the low-frequency part of the basilar membrane is masked.     

Effective equation of nonlinear pulse evolution in a randomly anisotropic medium

Propagation of a light pulse through a weakly inhomogeneous optical fiber is analyzed. The non-linear envelope equation describing the evolution of polarized pulses is determined by statistical properties of inhomogeneities in the optical fiber. The isotropic Manakov system of equations is shown to be applicable in the presence of high-frequency small-scale defects in the fiber. In the presence of only large-scale inhomogeneities, the signal dynamics are described by an anisotropic system of equations.