Effect of roving on spatial release from masking for amplitude modulated noise stimuli
Norbert Kopco, Jaclyn J. Jacobson, and Barbara G. Shinn-Cunningham
A previous study investigating detection of broadband signals embedded in broadband noise showed that detection thresholds depended both on the temporal structure of the target and masker and their simulated spatial locations [Kopco and Shinn-Cunningham, J. Acoust. Soc. Am. 117, 2396, 2005].� The current study extends this work by introducing a rove in overall intensity to reduce the reliability of overall intensity cues for detecting the target.
Detection thresholds were measured for a broadband noise target spectrally and temporally centered within a broadband noise masker. Thresholds were measured for all combinations of six spatial configurations of target and masker and five modulation conditions (all combinations of target modulated and unmodulated and of masker modulated and unmodulated; when both target and masker were modulated, the modulation could either be equal or pi out of phase). The amplitude modulation, if present, had a rate of 40 Hz and depth of 0.5. The masker level was roved by +/-5dB between intervals within a trial.
Results suggest that the cues underlying target detection depend on both the spatial configuration of target and masker and their temporal structure, but� that, when available, overall intensity cues also contribute to a target detection.
[Work supported by NSF and ONR]