Comodulation masking release in an off-frequency masking paradigm.
Detection threshold of a sinusoidal signal masked by a broadband masker is lower when on- and off-frequency masker components have a correlated envelope, compared to a condition in which these masker components have different envelopes. This effect is commonly referred to as comodulation masking release (CMR). The present study investigated if there is a CMR in the absence of a masker component at the signal frequency, i.e., in an off-frequency masking paradigm. Thresholds were measured for a 500-Hz signal in the presence of a broadband masker with a spectral notch at the signal frequency. Thresholds were significantly lower for a (co-)modulated than for an unmodulated masker for all notch widths up to 400 Hz. An additional experiment showed that the particularly large CMR for the no-notch condition was due to the way the modulated masker was generated. No CMR was measured when the notched-noise masker was replaced by a pair of narrowband noises. The addition of more remote masker bands resulted in a CMR of about 3-4 dB. The notched-noise data were predicted on the basis of a modulation-filterbank model. The predictions of the narrowband noise conditions indicated that all mechanisms underlying CMR might still not be fully understood.
Department of Experimental Audiology, Otto von Guericke University Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany.
Ramona
R
Grzeschik
Department of Experimental Audiology, Otto von Guericke University Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany.
Björn
B
Lübken
Department of Experimental Audiology, Otto von Guericke University Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany.
Jesko L
JL
Verhey