Temporal effects in simultaneous masking with on- and off-frequency noise maskers: effects of signal frequency and masker level.

International audienceTemporal effects in simultaneous masking were measured as a function of masker level for anon-frequency broadband masker and an off-frequency narrow-band masker for signal frequencies of750, 1730, and 4000 Hz. The on-frequency masker was 10 equivalent rectangular bandwidths~ERBs! wide and centered at the signal frequency; the off-frequency masker was 500 Hz wide andits lower frequency edge was 1.038 ERBs higher in frequency than the signal. The primary goal ofthe study was to determine whether previously observed differences regarding the effects of signalfrequency and masker level on the temporal effect for these two different types of masker might bedue to considerably different signal levels at threshold. Despite similar masked thresholds, theeffects of signal frequency and masker level in the present study were different for the two maskertypes. The temporal effect was significant for the two highest frequencies and absent for the lowestfrequency in the presence of the broadband masker, but was more or less independent of frequencyfor the narrow-band masker. The temporal effect increased but then decreased as a function of levelfor the broadband masker ~at the two higher signal frequencies, where there was a temporal effect!,but increased and reached an asymptote for the narrow-band masker. Despite the different effects ofsignal frequency and masker level, the temporal effects for both types of masker can be understoodin terms of a basilar-membrane input–output function that becomes more linear during the courseof masker stimulation