DETECTION OF UNEXPECTED TONES IN GATED AND CONTINUOUS MASKERS

The effect of gating a wideband masker on the detectability of tones h aving unexpected frequencies was assessed using a probe-signal method. This method leads the listener to expect a target frequency by presen ting the signal most often at that frequency, and measures sensitivity to other unexpected frequencies via occasionally presented probe tone s. For 295-ms signals, the probe-signal contours (percent correct as a function of probe frequency) of two of four subjects were considerabl y broader for st 295-ms masker than for a continuous masker. For 5-ms signals, the probe-signal contours of four of five subjects were quite broad and similar for both gated and continuous maskers. When the pro be-signal contours were expressed as the attenuation in decibels of th e probes, the resulting ''probe-signal filters'' were frequently broad er than auditory filters measured using notched noise in the same subj ects. This suggests that subjects may monitor multiple auditory filter s under some conditions in the probe-signal task. Signal threshold ten ded to be higher for conditions showing wider probe-signal filters, in dicating a potential link between changes in signal threshold due to m asker gating and the number of frequency channels that are monitored.