Effects of roving level variation on monaural detection with a contralateral cue

Monaural detection with a contralateral cue (MDCC) was measured with and without a 20-dB overall roving level to determine the contribution of loudness to performance on this task. Psychometric functions were obtained for three normal-hearing subjects as a function of the signal-to-noise ratio for pure-tone and 1/3-oct noiseband signals at 500 and 4000 Hz with a wideband noise masker. At 4000 Hz, the roving level degrades performance for the narrow-band noise signal by about 5.3 dB. In addition, the presence of the contralateral cue degrades performance for both the pure-tone and narrow-band noise signals at 4000 Hz by 3 to 6 dB. At 500 Hz, however, performance is not affected by the roving level, and is improved by 3 to 6 dB by the contralateral cue. These results indicate that loudness is being used as a cue only for detection of the 4000-Hz narrow-band noise.